Special Senses & Otolaryngology

Sinusitis: acute bacterial vs viral and management

Clinical Overview and When to Suspect Acute Sinusitis

— Viral (>90–98%): rhinovirus, influenza, parainfluenza, coronavirus, RSV, adenovirus

— Bacterial (~0.5–2%): Streptococcus pneumoniae, Haemophilus influenzae (often β-lactamase producing), Moraxella catarrhalis; S. aureus in chronic/complicated cases

— Fungal (invasive): immunocompromised, diabetic ketoacidosis — separate emergent track

— Persistent symptoms ≥10 days without improvement

— Severe onset: fever ≥39°C (102.2°F) AND purulent nasal discharge or facial pain for ≥3–4 consecutive days at illness onset

— "Double sickening": typical viral URI that improves then worsens after 5–6 days (new fever, headache, increased nasal discharge)

Acute rhinosinusitis (ARS) = symptomatic inflammation of the paranasal sinuses and nasal cavity lasting <4 weeks; subacute 4–12 weeks; chronic >12 weeks

Etiology distribution in adults presenting to primary care:

Pathophysiology: viral URI → mucosal edema at osteomeatal complex → impaired mucociliary clearance → stasis → secondary bacterial overgrowth

When to suspect acute bacterial rhinosinusitis (ABRS) — IDSA/AAO-HNS criteria, any ONE of:

Risk factors: prior viral URI, allergic rhinitis, anatomic obstruction (deviated septum, polyps), smoking, dental infection (maxillary), immunodeficiency, CF, ciliary dyskinesia

Board pearl: Purulent nasal discharge alone does not distinguish viral from bacterial — both can produce yellow-green secretions because of neutrophil myeloperoxidase. Duration and pattern are the discriminators, not color.

Step 3 ambulatory framing: most ARS presentations are opportunities to avoid antibiotics, document symptom duration carefully, and provide a safety-net follow-up plan — this aligns with Choosing Wisely and antimicrobial stewardship metrics tied to value-based care.

Presentation Patterns and Key History

— Purulent nasal discharge (anterior or posterior drip)

— Nasal obstruction/congestion

— Facial pain, pressure, or fullness — worse with bending forward, Valsalva

— Hyposmia or anosmia

— Days 1–5: symptoms peak then begin improving → viral

— Days 5–10: steady improvement → viral resolving

— ≥10 days without improvement → suspect ABRS

— Improvement then worsening at day 5–6 → double sickening → ABRS

— Maxillary: cheek pain, upper molar pain (consider odontogenic source — unilateral foul-smelling discharge)

— Frontal: forehead pain, worse leaning forward — highest complication risk

— Ethmoid: retro-orbital/medial canthal pain, periorbital edema

— Sphenoid: vertex or occipital headache, retro-orbital — rare but dangerous

— Visual changes, diplopia, proptosis → orbital cellulitis/abscess

— Severe unilateral headache, altered mental status, focal neuro deficit, seizure → intracranial extension

— Periorbital swelling/erythema in a child → preseptal vs orbital cellulitis triage

— Immunocompromise + facial pain + black nasal eschar → invasive fungal sinusitis (mucormycosis) — emergency

Cardinal symptoms (need ≥2 for clinical diagnosis of rhinosinusitis):

Supporting symptoms: maxillary dental pain, ear fullness, cough (especially nocturnal from postnasal drip), fatigue, halitosis, fever

Time course is the single most important historical element:

Sinus-specific localization clues:

Red-flag history (suggests complication or alternative dx):

Key distinction: A patient with 7 days of green nasal discharge who feels better today than yesterday has resolving viral sinusitis — antibiotics are not indicated regardless of secretion color or sinus tenderness.

Ask about: prior episodes (recurrent ABRS = ≥4/year warrants ENT), allergies, asthma (united airway), dental work, swimming/diving, prior sinus surgery, intranasal drug use, immunosuppression, and tobacco/vape exposure.

Physical Exam Findings

— Low-grade fever common in both viral and bacterial

— T ≥39°C (102.2°F) at presentation supports severe ABRS criterion

— Tachycardia/hypotension → consider sepsis or complication

— Tenderness to palpation/percussion over maxillary or frontal sinuses (modest specificity)

— Transillumination: opacification suggests fluid — operator-dependent, low sensitivity, not required

— Periorbital edema, erythema, proptosis, ophthalmoplegia, decreased visual acuity → orbital complication

— Forehead swelling ("Pott puffy tumor") → frontal osteomyelitis with subperiosteal abscess

— Mucosal erythema and edema

— Purulent discharge from middle meatus (maxillary, anterior ethmoid, frontal drainage) — most specific finding

— Polyps (suggests chronic disease or AERD)

— Septal deviation, foreign body (especially pediatrics with unilateral foul discharge)

General appearance: most patients are well-appearing; toxic appearance should prompt evaluation for complication

Vitals:

Head and face:

Nasal exam (anterior rhinoscopy):

Oropharynx: cobblestoning of posterior wall from postnasal drip; purulent drainage; dental caries/abscess of upper molars

Ears: TM retraction or effusion from eustachian dysfunction

Neurologic screen (mandatory if red flags): cranial nerves (especially II, III, IV, V1/V2, VI), meningeal signs, mental status

Lymph nodes: anterior cervical lymphadenopathy possible in either viral or bacterial

Step 3 management: In the ambulatory setting, document a focused neuro and ocular exam in any patient with frontal/ethmoid symptoms — this is the medicolegal anchor that protects against missed orbital/intracranial complications and supports your decision to defer imaging.

Board pearl: Unilateral facial pain + foul-smelling purulent discharge + upper molar tenderness = odontogenic maxillary sinusitis — anaerobic coverage (amoxicillin-clavulanate) and dental evaluation are required; this subset often fails standard therapy.

Diagnostic Workup — Initial Evaluation

— Toxic appearance, suspected sepsis (CBC, lactate, blood cultures, CMP)

— Immunocompromised host (CBC with differential, consider HIV, immunoglobulin levels if recurrent)

— Suspected complication (CBC, CRP, ESR, blood cultures)

— Plain sinus radiographs: obsolete; poor sensitivity and specificity

— Routine CT/MRI in straightforward outpatient ARS: low yield, contributes to overuse and incidental findings

— Suspected orbital or intracranial complication → CT face/sinuses + orbits with IV contrast, often plus CT or MRI brain with contrast

— Recurrent (≥4 episodes/year) or chronic sinusitis → non-contrast CT sinuses (preferred coronal cuts) to assess osteomeatal complex anatomy

— Immunocompromised with concern for invasive fungal disease → CT and urgent ENT

— Failure of second-line antibiotic therapy

— Reserved for treatment failure, immunocompromise, nosocomial sinusitis, or planned surgery

— Performed by ENT; replaces older standard of sinus puncture

ARS is a clinical diagnosis. Routine labs, cultures, and imaging are not recommended for uncomplicated cases.

Laboratory testing — generally NOT indicated; obtain only if:

Imaging — do NOT order for uncomplicated ARS (IDSA, AAO-HNS, ACR Appropriateness Criteria):

Imaging IS indicated when:

Nasal endoscopy with culture from middle meatus:

Routine cultures of nasal swabs are unhelpful — they reflect colonizing flora, not sinus pathogens

CCS pearl: On CCS, if you order "CT sinuses" for an otherwise classic 11-day uncomplicated ABRS case, expect a points deduction for unnecessary imaging. Order CT only when the case features periorbital findings, neuro signs, immunocompromise, or treatment failure.

Biomarkers: CRP/procalcitonin are studied but not standard for ARS triage in US guidelines; high CRP modestly favors bacterial but does not override clinical criteria

Document: symptom onset date, trajectory (improving/worsening/double sickening), severity criteria met, red-flag review of systems negative — this documentation is the workup in ambulatory ARS.

Diagnostic Workup — Advanced or Confirmatory Studies

— Treatment failure after 7 days of appropriate first-line antibiotic

— Recurrent ABRS (≥4 documented episodes/year with symptom-free intervals)

— Chronic rhinosinusitis (>12 weeks of symptoms)

— Suspected complication

— Immunocompromised host

— Unilateral disease (rule out neoplasm, fungal ball, foreign body)

— Assesses osteomeatal complex patency, mucosal thickening, air-fluid levels, anatomic variants (concha bullosa, Haller cells)

— Required preoperatively for functional endoscopic sinus surgery (FESS)

— Orbital cellulitis/abscess, subperiosteal abscess, cavernous sinus thrombosis, epidural/subdural empyema

— Intracranial extension, cavernous sinus thrombosis, optic nerve involvement, dural enhancement

— Differentiating tumor from inflammatory disease

— Gold-standard microbiologic sampling

— Identifies resistant organisms, anaerobes, S. aureus (including MRSA), Pseudomonas (CF), fungal elements

— Skin-prick or specific IgE testing

— Total IgE (elevated in AERD, allergic fungal sinusitis)

— Quantitative immunoglobulins (IgG, IgA, IgM, IgE)

— IgG subclasses

— Pneumococcal antibody titers pre- and post-vaccination (specific antibody deficiency)

— HIV testing

— Consider CF sweat chloride (especially young adults with nasal polyps), ciliary studies (primary ciliary dyskinesia)

Indications for advanced workup:

CT sinuses without contrast — workhorse advanced study:

CT with IV contrast — when complication suspected:

MRI brain/orbits with contrast — superior for:

Nasal endoscopy with culture (ENT):

Allergy workup for recurrent/chronic disease:

Immunologic workup for recurrent ABRS without clear anatomic cause:

Biopsy indications: unilateral mass, suspected neoplasm, granulomatous disease (GPA), invasive fungal disease (frozen section for hyphae)

Key distinction: Allergic fungal sinusitis = immunocompetent host, eosinophilic mucin with non-invasive hyphae, often nasal polyps; invasive fungal sinusitis = immunocompromised/diabetic, tissue invasion, black eschar, surgical emergency. Both need ENT but management diverges drastically.

Board pearl: Unilateral chronic sinusitis with epistaxis in an adult mandates ENT referral and imaging to rule out sinonasal malignancy (SCC, esthesioneuroblastoma) — do not just escalate antibiotics.

Risk Stratification and First-Line Management Logic

— Viral rhinosinusitis (most cases) → symptomatic care only

— ABRS by IDSA criteria → consider antibiotics vs watchful waiting

— Complicated/severe → urgent imaging + IV antibiotics + ENT

— Watchful waiting (AAO-HNS preferred for uncomplicated ABRS in adults):

– Offer if reliable follow-up exists and symptoms not severe

– Reassess at 7 days; begin antibiotics if no improvement or worsening

– Provide "safety-net" or delayed prescription — patient fills only if not improved by day 7

— Immediate antibiotics: severe symptoms, high fever, comorbidities (DM, immunocompromise, COPD, CHF), age >65, frailty, prior antibiotic use within 4–6 weeks, complications suspected

— Intranasal saline irrigation (high-volume, low-pressure with sterile/distilled water) — best-supported adjunct

— Intranasal corticosteroids (fluticasone, mometasone) — modest benefit, especially with allergic component

— Analgesics: acetaminophen, NSAIDs

— Oral or topical decongestants: short-term (≤3 days for topical to avoid rhinitis medicamentosa); avoid in HTN, CAD, glaucoma, BPH

— Avoid systemic antihistamines unless allergic rhinitis present (thicken secretions)

— Avoid systemic glucocorticoids in uncomplicated ARS (not recommended)

Step 1 — Classify the episode:

Step 2 — For ABRS, choose between "watchful waiting" vs immediate antibiotics:

Step 3 — Symptomatic adjuncts (recommend in ALL ARS regardless of etiology):

Step 3 management: The board-correct answer for a patient on day 8 of URI with mild bilateral facial pressure and yellow discharge who is improving is saline irrigation + intranasal steroid + reassurance, NOT amoxicillin-clavulanate. Recognize the trap.

Stewardship framing: antibiotic prescribing for ARS is a tracked HEDIS/quality metric; appropriate non-prescription supports value-based payment goals

Board pearl: Patients often equate "sinus infection" with "needs antibiotics." Effective shared decision-making — explaining natural history and offering delayed prescriptions — reduces antibiotic use by ~40% without increasing complications.

Pharmacotherapy — First-Line Antibiotic Regimens

— Amoxicillin-clavulanate 500 mg/125 mg PO TID or 875 mg/125 mg PO BID × 5–7 days

— Preferred over amoxicillin alone due to rising β-lactamase–producing H. influenzae and M. catarrhalis

— AAO-HNS still lists amoxicillin ± clavulanate; IDSA prefers clavulanate-containing

— Age ≥65, recent hospitalization, antibiotic use in past month

— Immunocompromised

— Severe infection, comorbidities

— Regions with >10% penicillin-non-susceptible S. pneumoniae

— Daycare attendance (pediatrics)

— Non-severe/non-IgE (rash, unclear history): doxycycline 100 mg PO BID, or cefuroxime/cefpodoxime/cefdinir (cross-reactivity with modern cephalosporins <2%)

— Severe/IgE-mediated (anaphylaxis, SJS): doxycycline is first choice; alternatives are levofloxacin 500 mg daily or moxifloxacin 400 mg daily — reserve fluoroquinolones due to FDA black-box warnings (tendinopathy, aortic aneurysm, QT, dysglycemia, neuropathy, mental health effects)

— Macrolides (azithromycin, clarithromycin) — ~30% pneumococcal resistance

— TMP-SMX — high resistance

— Second/third-gen oral cephalosporins as monotherapy for pneumococcus

— No improvement at 72 hours → switch to high-dose amoxicillin-clavulanate or doxycycline; consider ENT referral

— Worsening on therapy → CT imaging, ENT for endoscopy/culture, consider levofloxacin

First-line for ABRS in adults (IDSA 2012):

High-dose amoxicillin-clavulanate (2 g/125 mg ER PO BID) — indicated when:

Penicillin allergy:

Avoid as monotherapy (high resistance rates among S. pneumoniae and H. influenzae):

Duration: 5–7 days in adults with uncomplicated ABRS (10–14 days in children, severe, or immunocompromised)

Expected response: clinical improvement within 48–72 hours

Treatment failure pathway:

Board pearl: Azithromycin is the wrong answer for ABRS on Step 3 — pneumococcal macrolide resistance is too high. Pick amoxicillin-clavulanate unless allergy or specific contraindication dictates otherwise.

CCS pearl: Order "amoxicillin-clavulanate PO" with explicit duration and schedule a phone or office follow-up at 72 hours and 7 days — both follow-up touchpoints score on CCS.

Expanded Pharmacology and Adjunctive Therapies

— Fluticasone propionate 50 mcg 2 sprays each nostril daily, or mometasone 50 mcg 2 sprays each nostril daily

— Mechanism: reduces mucosal edema at osteomeatal complex

— Modest reduction in symptom duration; greater benefit in patients with allergic rhinitis

— Safe long-term; counsel on technique (aim laterally, away from septum) to prevent epistaxis and rare septal perforation

— High-volume (≥200 mL) low-pressure devices (neti pot, squeeze bottle) outperform sprays

— Use distilled, sterile, or previously boiled water — tap water risks Naegleria fowleri (rare but fatal amebic meningoencephalitis)

— Daily during acute episode; can continue chronically

— Topical oxymetazoline: ≤3 days; longer causes rhinitis medicamentosa

— Oral pseudoephedrine: avoid in HTN (raises BP), CAD, hyperthyroidism, BPH, narrow-angle glaucoma, MAOI use, pregnancy first trimester

— Phenylephrine PO: oral bioavailability poor; recent FDA advisory deems it ineffective

— Complications: orbital abscess drainage, intracranial abscess drainage (neurosurgery + ENT)

— Refractory chronic rhinosinusitis after maximal medical therapy: functional endoscopic sinus surgery (FESS) restores ostiomeatal drainage

— Balloon sinuplasty: office-based dilation for select chronic cases

— Biologics (dupilumab, omalizumab, mepolizumab): FDA-approved for CRS with nasal polyps refractory to surgery/steroids — type 2 inflammation pathway

Intranasal corticosteroids (INCS) — recommended adjunct in ABRS and viral ARS:

Saline nasal irrigation:

Decongestants:

Analgesics: acetaminophen, NSAIDs (ibuprofen, naproxen) — round-the-clock dosing better than PRN

Mucolytics (guaifenesin): weak evidence; reasonable adjunct

Antihistamines: only if concomitant allergic rhinitis — second-generation (loratadine, cetirizine, fexofenadine) preferred; first-generation thicken secretions and sedate

Systemic corticosteroids: not recommended for uncomplicated ARS; consider only for severe nasal polyposis or AERD under specialist care

Procedural/surgical management — reserved for:

Key distinction: Antibiotics + INCS + saline = the outpatient triad for ABRS. INCS + saline alone (no antibiotic) = the answer for viral ARS or mild ABRS with watchful waiting. Memorize both pathways.

Special Populations — Elderly and Renal/Hepatic Impairment

— Lower threshold to treat ABRS with antibiotics rather than watchful waiting (per IDSA/AAO-HNS modifying factors)

— High-dose amoxicillin-clavulanate (2 g/125 mg ER BID) often preferred given comorbidity burden, frailty, prior antibiotic exposure

— Atypical presentations: less fever, more fatigue/confusion; rule out delirium drivers

— Polypharmacy concerns:

– Avoid first-gen antihistamines (anticholinergic load, falls — Beers criteria)

– Avoid systemic decongestants (HTN, urinary retention in BPH, arrhythmia)

– Doxycycline: photosensitivity, esophagitis (take with water, upright 30 min)

– Fluoroquinolones: tendon rupture risk increases with age and concurrent glucocorticoids; QT prolongation with amiodarone/sotalol/macrolides; avoid when possible in elderly

— Amoxicillin-clavulanate dose adjust:

– CrCl 10–30: 500 mg amox component q12h

– CrCl <10 or HD: 500 mg q24h; dose after dialysis

– Do NOT use 875 mg BID or ER formulation if CrCl <30 (clavulanate accumulates → hepatotoxicity)

— Levofloxacin: adjust below CrCl 50; risk of dysglycemia in CKD + sulfonylureas

— Doxycycline: no renal adjustment needed — useful in CKD

— NSAIDs: avoid or minimize in CKD stage ≥3, CHF, cirrhosis with ascites

— Amoxicillin-clavulanate: rare cholestatic hepatitis — caution and counsel in pre-existing liver disease; monitor LFTs if prolonged courses

— Doxycycline: generally safe; avoid in severe hepatic dysfunction

— Acetaminophen: limit to ≤2 g/day in cirrhosis or active alcohol use

— Hyperglycemia worsens with fluoroquinolone use (both hypo- and hyperglycemia documented); monitor glucose

— Uncontrolled DM + facial pain + black turbinate/eschar + cranial neuropathy = mucormycosis — emergent ENT consult, liposomal amphotericin B, surgical debridement, glycemic correction (treat DKA if present)

Elderly (≥65 years):

Renal impairment:

Hepatic impairment:

Diabetes mellitus:

Step 3 management: In an 80-year-old with ABRS, CrCl 25, on warfarin: prescribe renally-adjusted amoxicillin-clavulanate (avoid ER), check INR within a few days (antibiotic-induced gut flora disruption can elevate INR), and avoid TMP-SMX or fluoroquinolones if possible (warfarin and QT/dysglycemia interactions).

Board pearl: Amoxicillin-clavulanate is the leading cause of drug-induced cholestatic hepatitis, typically 1–6 weeks after exposure; usually self-limited but recurs on re-challenge — document and add to allergy list.

Special Populations — Pregnancy and Pediatrics

— Symptomatic care first: saline irrigation, intranasal corticosteroids (budesonide, fluticasone, mometasone — Category B/C, generally considered safe), acetaminophen

— Avoid NSAIDs after 20 weeks (renal/oligohydramnios) and in third trimester (premature ductal closure)

— Avoid pseudoephedrine in first trimester (gastroschisis association); use sparingly later if BP normal

— Antibiotics when ABRS criteria met:

– Amoxicillin or amoxicillin-clavulanate — first line, safe

– Cephalosporins (cefuroxime, cefpodoxime) — safe

– Avoid doxycycline (teeth staining, bone after week 15) — generally contraindicated

– Avoid fluoroquinolones (cartilage concerns)

– Avoid TMP-SMX in first trimester (folate antagonism, NTDs) and near term (kernicterus)

— Pregnancy rhinitis: hormonally mediated congestion, often confused with sinusitis; lacks purulence and facial pain

— Same three diagnostic patterns: persistent ≥10 days, severe (fever ≥39°C + purulent discharge ≥3 days), or worsening course

— Symptomatic care + watchful waiting acceptable for persistent mild presentations; immediate antibiotics for severe or worsening course

— First-line: amoxicillin 45 mg/kg/day divided BID; high-dose amoxicillin 80–90 mg/kg/day divided BID with clavulanate preferred in:

– Age <2, daycare attendance, recent antibiotics, severe disease, areas with high pneumococcal resistance

— Duration: 10–14 days (or 7 days after symptom resolution)

— Penicillin allergy: cefdinir, cefuroxime, cefpodoxime; clindamycin + cefixime for severe allergy; levofloxacin only if no alternative

— Avoid OTC cough/cold preparations in children <4 years (FDA warning — risk > benefit)

— Periorbital swelling → distinguish preseptal (preserved EOM, vision) from orbital cellulitis (proptosis, painful EOM, decreased acuity) → CT orbits with contrast, IV antibiotics (vancomycin + ceftriaxone ± metronidazole), ENT/ophthalmology

— Unilateral foul nasal discharge in a toddler → nasal foreign body until proven otherwise

Pregnancy:

Pediatrics (modified IDSA/AAP criteria, ages 1–18):

Pediatric red flags:

Board pearl: A child with sinusitis symptoms plus periorbital edema needs CT with contrast and admission, not an outpatient amoxicillin prescription. Orbital cellulitis is the classic pediatric sinusitis complication.

Complications and Adverse Outcomes

— I: Preseptal (periorbital) cellulitis — anterior to orbital septum; EOM and vision intact

— II: Orbital cellulitis — proptosis, chemosis, painful/limited EOM, decreased acuity

— III: Subperiosteal abscess — pus between periosteum and bone

— IV: Orbital abscess — within orbital fat

— V: Cavernous sinus thrombosis — bilateral findings, CN III/IV/V1/V2/VI deficits, sepsis

— Management: CT orbits with contrast, IV vancomycin + ceftriaxone (+ metronidazole if intracranial concern), urgent ENT + ophthalmology; surgical drainage for abscess or vision threat

— Meningitis, epidural abscess, subdural empyema, brain abscess, cerebritis

— Presentation: severe headache, fever, altered mental status, focal deficits, seizures, meningismus

— Workup: MRI brain with contrast (preferred), CT with contrast if MRI unavailable; LP only after imaging excludes mass effect

— Treatment: vancomycin + ceftriaxone + metronidazole IV; neurosurgical drainage as needed

— Bilateral periorbital edema, proptosis, ophthalmoplegia (CN III, IV, VI), V1/V2 sensory loss, papilledema

— MRI/MRV diagnostic

— IV broad-spectrum antibiotics; anticoagulation controversial but commonly used

— Immunocompromised, DKA, neutropenic, transplant

— Black necrotic eschar on turbinates or palate, rapidly progressive pain, cranial neuropathies

— Emergent surgical debridement + liposomal amphotericin B; treat underlying immunosuppression/DKA

— High mortality (>50%)

Orbital complications (Chandler classification) — most commonly from ethmoid sinusitis via lamina papyracea:

Intracranial complications (often from frontal or sphenoid sinusitis):

Cavernous sinus thrombosis:

Pott puffy tumor: subperiosteal abscess of frontal bone with osteomyelitis — doughy forehead swelling; classic adolescent presentation; needs surgical drainage + prolonged IV antibiotics (4–6 weeks)

Invasive fungal sinusitis (mucormycosis, aspergillosis):

Chronic rhinosinusitis (>12 weeks): may follow inadequately treated/recurrent ABRS; impacts QOL, work productivity

Antibiotic-related adverse events: C. difficile colitis, rash, anaphylaxis, hepatitis (amox-clav), tendinopathy (FQ), photosensitivity (doxy)

Key distinction: Preseptal cellulitis = outpatient oral antibiotics often acceptable in mild cases with reliable follow-up; orbital cellulitis = inpatient IV antibiotics, imaging, multidisciplinary care. EOM and vision are the dividing line.

When to Escalate Care — ED, Inpatient, and Consults

— Suspected orbital cellulitis or abscess (proptosis, painful EOM, vision change)

— Suspected intracranial complication (severe headache, altered mental status, focal neuro signs, meningismus, seizure)

— Cavernous sinus thrombosis features (bilateral orbital findings, multiple CN palsies)

— Pott puffy tumor (frontal bone swelling)

— Invasive fungal sinusitis suspicion in immunocompromised/DKA — emergent

— Sepsis physiology (hypotension, tachycardia, lactic acidosis, qSOFA ≥2)

— Inability to tolerate oral intake or antibiotics

— Severe immunocompromise (neutropenia, post-transplant, advanced HIV)

— Admit to floor (ICU if airway/vision/CNS threat or septic)

— NPO if surgery anticipated; IV fluids

— IV antibiotics: vancomycin + ceftriaxone (add metronidazole for intracranial or anaerobic/odontogenic concern; broaden to piperacillin-tazobactam or meropenem in hospital-acquired or immunocompromised cases)

— Imaging: CT face/orbits with contrast; MRI brain with contrast if intracranial concern

— Consults: ENT (drainage, endoscopy with culture), ophthalmology (visual acuity, IOP, RAPD checks q4h for orbital cases), neurosurgery (intracranial collections), infectious disease (immunocompromised, atypical organisms, prolonged courses), endocrinology (DKA correction for mucormycosis)

— DVT prophylaxis, glycemic control, pain management

— ENT (otolaryngology):

– Recurrent ABRS (≥4/year)

– Chronic rhinosinusitis (>12 weeks)

– Treatment failure after 2 antibiotic courses

– Suspected anatomic obstruction or polyps

– Unilateral disease (rule out neoplasm)

— Allergy/immunology: allergic rhinitis workup, immunodeficiency evaluation, AERD, biologic therapy candidacy

— Dental: suspected odontogenic source (unilateral maxillary disease with dental pain)

— Pulmonology: suspected CF, primary ciliary dyskinesia, asthma–sinusitis (united airway)

Immediate ED referral / inpatient admission:

Inpatient management essentials (CCS-style):

Outpatient specialty referral (non-urgent):

CCS pearl: For an inpatient orbital cellulitis case, the sequence is: vitals → IV access → CT orbits with contrast → blood cultures → vancomycin + ceftriaxone → ENT consult → ophthalmology consult → serial vision checks. Forgetting serial visual acuity checks is a common deduction.

Step 3 management: Document a clear return-precaution list at every outpatient sinusitis visit — vision change, severe headache, neck stiffness, confusion, worsening fever, swelling around the eye — this transitions risk back to the patient appropriately and protects against missed complications.

Key Differentials — Other Upper Airway/ENT Causes

— Symptoms peak day 2–3, resolve by day 7–10

— Lacks the IDSA temporal criteria for ABRS

— Treatment: symptomatic only — saline, analgesics, rest, hydration

— Chronic or seasonal; sneezing, itching (eyes, nose, palate), clear watery rhinorrhea

— Pale boggy turbinates, allergic shiners, transverse nasal crease ("allergic salute")

— Treatment: avoidance, intranasal steroids, antihistamines, leukotriene receptor antagonists, immunotherapy

— Triggered by weather changes, odors, food (gustatory); no IgE involvement

— Treatment: intranasal ipratropium, intranasal antihistamines (azelastine)

— Rebound congestion from prolonged topical decongestant use (>3 days)

— Treatment: stop offending agent, bridge with intranasal steroids

— Persistent congestion, hyposmia, recurrent acute exacerbations

— Associated with AERD (Samter triad: asthma, nasal polyps, ASA/NSAID sensitivity)

— Treatment: intranasal steroids, short oral steroid bursts, FESS, biologics (dupilumab, omalizumab, mepolizumab)

— Persistent unilateral obstruction; addressed surgically if symptomatic

— Unilateral foul purulent discharge in a child — remove and address

— Maxillary tooth abscess with sinus extension — dental imaging, dental treatment, antibiotic anaerobic coverage

— Unilateral persistent symptoms, epistaxis, facial numbness/pain, cranial nerve deficit

— Imaging + biopsy via ENT

— Saddle-nose deformity, septal perforation, crusting, c-ANCA/PR3 positive, pulmonary-renal involvement

— Treat with rituximab or cyclophosphamide + glucocorticoids

Viral upper respiratory infection (common cold):

Allergic rhinitis:

Non-allergic vasomotor rhinitis:

Rhinitis medicamentosa:

Nasal polyps / chronic rhinosinusitis with nasal polyps (CRSwNP):

Deviated septum / turbinate hypertrophy:

Nasal foreign body (pediatric):

Odontogenic infection:

Sinonasal neoplasm:

Granulomatosis with polyangiitis (GPA):

Key distinction: Unilateral, persistent, treatment-resistant sinus symptoms in an adult should always prompt ENT referral and imaging — neoplasm, fungal ball, GPA, and foreign body all hide here. Bilateral symptoms are far more often benign rhinosinusitis.

Key Differentials — Non-ENT Causes of Facial Pain/Headache

— Throbbing, often unilateral, photophobia, phonophobia, nausea

— Frequently misdiagnosed as "sinus headache" — up to 90% of self-diagnosed sinus headaches without nasal symptoms are migraines

— Triggers: stress, hormonal, foods, sleep changes

— Treatment: triptans, gepants, NSAIDs; prophylaxis if frequent

— Bilateral, band-like, pressure quality; no nasal symptoms

— Severe unilateral periorbital pain with ipsilateral autonomic features (lacrimation, rhinorrhea, miosis, ptosis) — can mimic sinusitis

— Treatment: high-flow O₂, subcutaneous sumatriptan; verapamil prophylaxis

— Brief electric-shock-like facial pain in V2/V3 distribution, triggered by light touch

— Treatment: carbamazepine, oxcarbazepine

— Jaw/preauricular pain, worse with chewing, clicking, limited opening

— Temporal headache, jaw claudication, scalp tenderness, visual changes, elevated ESR/CRP

— Start prednisone immediately; temporal artery biopsy to confirm

— Severe eye pain, halos, fixed mid-dilated pupil, red eye, nausea — ophthalmologic emergency

Migraine:

Tension-type headache:

Cluster headache:

Trigeminal neuralgia:

Temporomandibular disorder (TMD):

Giant cell arteritis (age >50):

Dental pathology: apical abscess, pulpitis — can refer to maxillary region

Acute angle-closure glaucoma:

Idiopathic intracranial hypertension: young obese women, papilledema, transient visual obscurations

Cerebrospinal fluid rhinorrhea: clear unilateral nasal discharge after trauma or surgery — β2-transferrin testing; risk of meningitis

Atypical odontalgia, post-herpetic neuralgia, sinonasal tumors as discussed

Carotid/vertebral dissection: unilateral neck/face pain, Horner syndrome, stroke symptoms

Step 3 management: A patient with recurrent "sinus headaches," normal sinus exam, no purulence, photophobia, and family history of migraine should receive a migraine work-up and trial of triptans, not repeated antibiotic courses. Recognize this overdiagnosed scenario — it is a common Step 3 vignette.

Board pearl: "Sinus headache" without objective sinus findings (purulence, obstruction, hyposmia) is most often migraine; treating it as ABRS perpetuates antibiotic overuse and delays correct therapy.

Discharge Planning, Secondary Prevention, and Long-Term Strategy

— Written instructions: medication name, dose, duration, what to expect

— Symptomatic adjuncts: saline irrigation technique demo, intranasal steroid technique, analgesia plan

— Return precautions: vision change, severe headache, neck stiffness, periorbital swelling, confusion, persistent fever >72 hours on antibiotics, symptoms worse after initial improvement

— Follow-up appointment or phone check at 72 hours (response assessment) and 7–14 days

— Antibiotic stewardship counseling: explain why most "sinus infections" do not need antibiotics

— Smoking cessation — single most impactful modifiable risk factor (impairs mucociliary clearance); offer counseling and pharmacotherapy (varenicline, bupropion, NRT)

— Allergic rhinitis control: daily intranasal steroid, second-gen antihistamines, allergen avoidance, immunotherapy for severe cases

— Asthma optimization: united-airway concept — uncontrolled asthma worsens sinus disease

— Reflux management: LPR can perpetuate inflammation; lifestyle + PPI trial if indicated

— Dental care: treat maxillary caries/abscesses

— Saline irrigation as daily maintenance for prone patients

— Hand hygiene, influenza vaccination, COVID-19 vaccination — reduce viral URIs that precipitate ABRS

— Pneumococcal vaccination per ACIP for eligible adults (PCV15/PCV20, PPSV23 per current schedule) and children — reduces S. pneumoniae burden

— Humidification in dry climates; avoid environmental irritants

— Recurrent ABRS (≥4 episodes/year): ENT for endoscopy/CT; allergy/immunology workup

— Chronic rhinosinusitis: 12-week trial of intranasal steroids + saline ± targeted antibiotics; consider FESS or biologic therapy

End-of-visit checklist for ABRS:

Secondary prevention strategies:

Chronic/recurrent disease pathway:

Update problem list and allergy list with antibiotic reactions; specify reaction type (rash vs anaphylaxis vs intolerance) — improves future prescribing

Step 3 management: Build the post-acute plan into the same visit — schedule the 7-day follow-up, send the smoking cessation referral, update vaccinations, document the allergic rhinitis plan. This longitudinal thinking is what differentiates Step 3 from Step 2.

Board pearl: A patient with three ABRS episodes in 8 months plus seasonal nasal symptoms should receive daily intranasal steroid + allergy referral, not a fourth antibiotic course on demand.

Follow-Up, Monitoring, and Counseling

— 72 hours: phone or office check — expected clinical improvement; if no improvement, reassess diagnosis and consider switching to high-dose amoxicillin-clavulanate or doxycycline; if worsening, image and refer ENT

— 7 days (or end of antibiotic course): confirm resolution; assess for need for additional therapy

— 2–4 weeks: if symptoms persist or recurrence; consider ENT referral

— For watchful waiting: reassess at day 7; initiate antibiotics if no improvement

— Symptom diary: pain, congestion, discharge, fever, functional status

— Vital signs at each visit

— INR for warfarin patients on antibiotics (amox-clav, doxycycline, FQ all interact)

— Glucose monitoring in diabetics on fluoroquinolones

— LFTs if prolonged amox-clav or doxycycline

— Realistic expectations: viral ARS lasts up to 2 weeks; ABRS improves within 72 hours of appropriate antibiotic

— Importance of completing the prescribed antibiotic course

— Saline irrigation technique: distilled/sterile water; tilt head, breathe through mouth

— Intranasal steroid technique: aim laterally toward ipsilateral ear, not at septum

— Avoid prolonged topical decongestant use (rebound)

— Smoking cessation: every visit is a quit attempt opportunity

— Hand hygiene and respiratory etiquette

— Vaccination status review (influenza, COVID-19, pneumococcal)

— When to seek emergency care (red-flag list above)

— Allergen reduction (HEPA filtration, dust-mite covers, pet dander management)

— Indoor humidity 30–50%

— Hydration and steam inhalation for symptom comfort

— Sleep hygiene and stress reduction (immune effects)

— Document IDSA criteria explicitly when prescribing antibiotics

— Track delayed prescription use as a stewardship indicator

— Use shared decision-making tools where available

Follow-up cadence for ABRS:

Monitoring parameters:

Counseling priorities:

Rehabilitation/lifestyle for chronic/recurrent disease:

Quality and stewardship metrics:

CCS pearl: On CCS, advancing the clock to "72 hours" and "7 days" with brief telephone follow-up orders captures the longitudinal scoring that Step 3 emphasizes. Don't simply prescribe and discharge — set the follow-up touchpoints explicitly.

Ethical, Legal, and Patient Safety Considerations

— Inappropriate antibiotic prescribing causes patient harm (CDI, allergic reactions, resistance) and population harm (community resistance)

— A patient's request for antibiotics is not, by itself, an indication; physicians have an ethical duty to decline non-indicated prescriptions while preserving the therapeutic relationship

— Use shared decision-making: explain natural history, offer delayed/safety-net prescriptions, document the conversation

— Off-label fluoroquinolone use carries FDA black-box warnings — document discussion of tendon rupture, aortic aneurysm, neuropathy, dysglycemia, mental health effects, especially in elderly or athletes

— INCS in pregnancy: discuss risk-benefit, document shared decision

— Pediatric antibiotic prescribing: parental shared decision-making; document

— Patient discharged from urgent care with antibiotic but no PCP follow-up — high risk of missing complications or treatment failure

— Mitigation: explicit return precautions, 72-hour check-in, electronic record sharing, warm handoff for high-risk patients (immunocompromised, frail elderly)

— Medication reconciliation across settings — antibiotic-warfarin and antibiotic-statin interactions are common harm vectors

— Record symptom duration, severity criteria, red-flag ROS, return precautions, follow-up plan — this is both clinical care and medicolegal protection

— Document allergy reactions specifically (rash vs anaphylaxis)

— Outbreaks of resistant pneumococcus or unusual organisms may warrant public health notification

— Suspected anthrax/biothreat sinonasal presentations are reportable

— Antibiotic overprescribing is more common in white, insured patients in some studies; underprescribing/delayed care in marginalized populations may risk complications

— Provide culturally tailored education and ensure access to follow-up

— Immunocompromised patients should not be offered watchful waiting — lower threshold for treatment and imaging

— Pediatric patients depend on caregiver reliability for return-precaution adherence; assess caregiver capacity

Antibiotic stewardship as ethical practice:

Informed consent edge cases:

Transition-of-care risks (Step 3 favorite):

Documentation safety net:

Mandatory reporting and public health:

Health equity:

Vulnerable populations:

Patient safety pearl: Tap-water neti pot use has caused fatal Naegleria fowleri primary amebic meningoencephalitis — explicitly counsel patients to use distilled, sterile, or previously boiled-and-cooled water. Including this safety instruction in the visit note is both clinical care and a documented safety event prevention.

Step 3 management: When declining to prescribe antibiotics for viral sinusitis, document: "Discussed natural history, return precautions, and rationale for non-antibiotic management; patient verbalized understanding and agreed to plan." This single sentence converts the encounter into defensible stewardship.

High-Yield Associations and Rapid-Fire Clinical Facts

>90% of acute rhinosinusitis is viral; ABRS is the exception, not the rule

Three IDSA criteria for ABRS: persistent ≥10 days, severe (T ≥39°C + purulent ≥3 days), or double sickening

Top bacterial pathogens: S. pneumoniae, H. influenzae, M. catarrhalis (children); add S. aureus and anaerobes in chronic/complicated/odontogenic disease

First-line antibiotic: amoxicillin-clavulanate (NOT azithromycin — macrolide resistance too high)

Duration: 5–7 days adults; 10–14 days children

Watchful waiting is acceptable for uncomplicated ABRS in adults with reliable follow-up

Adjuncts in every patient: saline irrigation + intranasal corticosteroid + analgesia

Tap water + neti pot = Naegleria fowleri risk → use distilled/sterile/boiled water

Purulent discharge color does NOT distinguish viral from bacterial

Periorbital edema in a child with sinusitis → CT orbits with contrast; orbital cellulitis until proven otherwise

Pott puffy tumor = frontal osteomyelitis + subperiosteal abscess; classic in adolescents

Cavernous sinus thrombosis = bilateral orbital findings + multiple CN palsies (III, IV, V1/V2, VI)

Mucormycosis = DKA or immunocompromised + black turbinate eschar + cranial neuropathy → emergent surgery + liposomal amphotericin B

Unilateral chronic sinusitis with epistaxis → image and biopsy; rule out sinonasal malignancy

Saddle-nose deformity + nasal crusting + lung/kidney disease → GPA; check c-ANCA/PR3

Samter triad = asthma + nasal polyps + ASA/NSAID sensitivity (AERD)

Unilateral foul nasal discharge in a child = foreign body until proven otherwise

Most "sinus headaches" without nasal symptoms are migraines

Avoid fluoroquinolones first-line — reserve for severe penicillin allergy or treatment failure; black-box warnings

Amoxicillin-clavulanate is the leading cause of drug-induced cholestatic hepatitis

Doxycycline is renally safe and useful in penicillin allergy (avoid in pregnancy/children <8)

Pediatric high-dose amoxicillin-clavulanate: 80–90 mg/kg/day divided BID

Pneumococcal and influenza vaccination reduce ABRS incidence

Smoking cessation is the most impactful modifiable risk factor for recurrent/chronic disease

Recurrent ABRS (≥4/year) → ENT, allergy, immunology workup

Chronic rhinosinusitis with polyps refractory to surgery → biologics (dupilumab, omalizumab, mepolizumab)

CRS = ≥12 weeks of symptoms with objective inflammation on exam or imaging

Board pearl: If the question mentions "yellow-green discharge" without duration or severity, the answer is not antibiotics — look for the temporal criteria.

Board Question Stem Patterns

— 35 yo with 5 days of yellow-green nasal discharge, mild facial pressure, low-grade fever, feeling slightly better. Most appropriate next step?

— Answer: Saline irrigation, intranasal corticosteroid, analgesia, reassurance — viral ARS, no antibiotics

— 42 yo with 12 days of nasal congestion, purulent discharge, facial pressure, no improvement. No fever. Most appropriate?

— Answer: Amoxicillin-clavulanate × 5–7 days (ABRS by persistent criterion)

— 28 yo with 4 days URI that began improving day 5, then on day 7 redeveloped fever, increased purulence, facial pain. Most appropriate?

— Answer: Amoxicillin-clavulanate (ABRS by worsening course)

— ABRS in patient with history of penicillin anaphylaxis. Best choice?

— Answer: Doxycycline (preferred); levofloxacin if doxycycline contraindicated

— Will always appear as a tempting wrong answer. Choose against it.

— Child with 8 days of URI, now with right eye swelling, pain with eye movement, decreased acuity. Next step?

— Answer: CT orbits with IV contrast + admit + IV vancomycin + ceftriaxone + ENT/ophthalmology consult

— Teen with frontal headache and forehead doughy swelling after URI. Diagnosis?

— Answer: Frontal osteomyelitis (Pott puffy tumor) → CT with contrast, IV antibiotics, surgical drainage

— Diabetic in DKA with facial pain, black turbinate eschar, ophthalmoplegia. Next step?

— Answer: Emergent ENT consult, surgical debridement, liposomal amphotericin B, correct DKA

— Recurrent "sinus headaches" with photophobia, normal sinus exam, family history of migraine. Best management?

— Answer: Trial of triptan; treat as migraine

— Adult with 6 months unilateral nasal obstruction, epistaxis, facial numbness. Next step?

— Answer: ENT referral with CT and biopsy — rule out sinonasal neoplasm

— Pregnant patient with ABRS criteria met. Best antibiotic?

— Answer: Amoxicillin or amoxicillin-clavulanate (avoid doxycycline, FQ, TMP-SMX)

— 3 yo with unilateral foul-smelling nasal discharge × 2 weeks. Next step?

— Answer: Nasal exam to identify and remove foreign body

Pattern 1 — The "color trap":

Pattern 2 — The "10-day persistent":

Pattern 3 — The "double sickening":

Pattern 4 — The "penicillin anaphylaxis":

Pattern 5 — The "azithromycin distractor":

Pattern 6 — The orbital complication:

Pattern 7 — The Pott puffy tumor:

Pattern 8 — Mucormycosis:

Pattern 9 — The migraine masquerader:

Pattern 10 — The unilateral red flag:

Pattern 11 — Pregnant patient:

Pattern 12 — Pediatric foreign body:

Step 3 management: Identify the temporal pattern first, then the modifying factors (allergy, comorbidity, complication features) — this two-step parse handles the vast majority of sinusitis vignettes.

One-Line Recap

Acute rhinosinusitis is overwhelmingly viral and self-limited; reserve antibiotics — first-line amoxicillin-clavulanate — for patients meeting IDSA criteria (≥10 days persistent, severe ≥39°C with purulence ≥3 days, or double-sickening), pair every case with saline irrigation and intranasal corticosteroids, and escalate urgently for orbital, intracranial, or invasive fungal complications.

Diagnostic anchor: ARS is clinical; CT and labs are reserved for complications, treatment failure, immunocompromise, or recurrent/chronic disease — not for routine diagnosis

Therapeutic anchor: Amoxicillin-clavulanate 875/125 mg BID × 5–7 days for ABRS in adults; high-dose for elderly, comorbid, or recent antibiotic exposure; doxycycline for penicillin allergy; never azithromycin first-line

Adjunct anchor: Saline irrigation (distilled/sterile water — avoid Naegleria) + intranasal corticosteroid + analgesia in every case, viral or bacterial

Safety anchor: Vision change, periorbital swelling, severe headache, altered mental status, focal neuro signs, immunocompromise with facial pain, or diabetic with black eschar → emergent imaging, IV antibiotics, and multidisciplinary admission

Longitudinal anchor: Smoking cessation, allergic rhinitis control, vaccination (influenza, pneumococcal, COVID-19), and ENT/allergy referral for recurrent (≥4/year) or chronic (>12 weeks) disease close the Step 3 loop

Board pearl: The classic Step 3 sinusitis question rewards the physician who doesn't prescribe antibiotics — recognize the viral pattern, document the conversation, prescribe symptom relief, schedule the 72-hour follow-up, and you will outscore the test-taker who reflexively writes for azithromycin.