Upper respiratory infections are the most common reason for outpatient antibiotic prescribing — and the most common reason for inappropriate antibiotic prescribing. The clinical skill is not choosing the right antibiotic. It is recognizing that most patients do not need one.
CLINICAL PRINTABLE
Coming Soon.
A one-page URI / Acute Sinusitis clinical reference is on the way.
1 · Recognition
- Viral URI (common cold): nasal congestion, rhinorrhea, sore throat, cough, low-grade fever. Symptoms peak at 2–3 days, resolve within 7–10 days. Caused by rhinovirus (most common), coronavirus, adenovirus, RSV, influenza.
- Viral sinusitis: facial pressure/pain, nasal congestion, purulent nasal discharge, reduced smell. Purulent discharge does NOT indicate bacterial infection — it is a normal part of viral URI. Symptoms typically resolve within 10 days.
- Bacterial acute rhinosinusitis (ABRS) — three clinical patterns: (1) Persistent symptoms ≥10 days without improvement; (2) Severe symptoms (fever ≥39°C, purulent nasal discharge, facial pain) for ≥3–4 consecutive days; (3) Double worsening — initial improvement followed by new worsening after day 5–6.
- Influenza: abrupt onset of fever, myalgia, headache, malaise, and respiratory symptoms. Distinguishable from common cold by severity and systemic features. Rapid influenza test has moderate sensitivity — treat empirically if clinical suspicion is high during flu season.
- Streptococcal pharyngitis mimics: viral pharyngitis, infectious mononucleosis (EBV), peritonsillar abscess. Centor/McIsaac criteria help stratify strep probability — but pharyngitis is covered in a separate Deep Dive.
2 · Differential / Mimics
Allergic rhinitis
Chronic or seasonal nasal congestion, clear rhinorrhea, sneezing, itchy eyes. No fever. Responds to antihistamines and intranasal corticosteroids, not antibiotics.
Influenza
Abrupt onset, high fever, prominent myalgia and malaise. Treat with oseltamivir within 48 hours of symptom onset for high-risk patients. Antiviral treatment reduces duration and severity.
COVID-19
Overlapping symptoms with URI. Loss of taste/smell is more specific for COVID-19. Test when clinical suspicion warrants or for infection control purposes.
Peritonsillar abscess
Unilateral tonsillar swelling, uvular deviation, muffled 'hot potato' voice, trismus. Requires drainage plus antibiotics. ENT referral.
3 · Treatment Pathway
Viral URI — symptomatic management
Saline nasal irrigation, decongestants (pseudoephedrine or oxymetazoline — limit oxymetazoline to 3 days to avoid rebound congestion), analgesics/antipyretics. Honey for cough in adults and children >1 year. Zinc lozenges within 24 hours may modestly reduce duration.
Viral sinusitis — symptomatic management
Intranasal saline irrigation, intranasal corticosteroids (modest benefit for symptom relief), analgesics. Decongestants for nasal congestion. Watchful waiting for 10 days — antibiotics are not indicated for viral sinusitis.
Bacterial acute rhinosinusitis (ABRS) — antibiotic therapy
Amoxicillin-clavulanate 875/125 mg twice daily for 5–7 days (adults). Amoxicillin alone is no longer preferred due to increasing beta-lactamase-producing H. influenzae. Doxycycline or respiratory fluoroquinolone for penicillin allergy.
Influenza — antiviral therapy
Oseltamivir 75 mg twice daily for 5 days. Greatest benefit when started within 48 hours of symptom onset. Treat regardless of time since onset in hospitalized patients, severe disease, or high-risk patients (elderly, immunocompromised, pregnant, chronic cardiopulmonary disease).
Watchful waiting for ABRS
For mild-moderate ABRS without severe symptoms, watchful waiting for 7 days with symptomatic treatment is an acceptable alternative to immediate antibiotics. Provide a backup prescription with instructions to fill if no improvement in 7 days.
4 · Expected Response
- Viral URI: symptoms peak at 2–3 days and resolve within 7–10 days. Cough may persist 2–3 weeks. Reassure patients that this is the expected course.
- ABRS with antibiotics: improvement expected within 3–5 days. If no improvement after 3–5 days of appropriate antibiotics, reassess — consider resistant organism, complication, or alternative diagnosis.
- Influenza with oseltamivir: reduces duration by approximately 1 day and reduces severity. Does not eliminate symptoms — set appropriate expectations.
5 · Escalation
- Orbital complications of sinusitis: periorbital edema, proptosis, restricted eye movement, vision changes — urgent CT sinuses and orbits, ophthalmology and ENT consultation, IV antibiotics.
- Intracranial complications: severe headache, meningismus, altered mental status, focal neurological deficits — urgent CT/MRI, neurosurgery and infectious disease consultation.
- Recurrent acute sinusitis (≥4 episodes/year) or chronic sinusitis (symptoms >12 weeks): ENT referral for endoscopic evaluation and possible functional endoscopic sinus surgery (FESS).
- Influenza with respiratory failure, secondary bacterial pneumonia, or high-risk patient deteriorating: hospitalization, IV oseltamivir, and management of complications.
Apply It · Change One Detail
APPLY IT
A 34-year-old presents on day 8 of nasal congestion, facial pressure, and purulent nasal discharge. She had some improvement around day 5 but has felt worse again for the past 2 days. This is the double-worsening pattern — initial viral URI followed by secondary bacterial sinusitis. Amoxicillin-clavulanate for 5–7 days is appropriate. The purulent discharge alone on day 3 would not have warranted antibiotics.
CHANGE ONE DETAIL
Change one detail — the same patient presents on day 6 with the same symptoms but no worsening after initial improvement, and no fever. She is still improving slowly. This is viral sinusitis on its expected course. Antibiotics are not indicated. Symptomatic management and reassurance that symptoms should resolve within 10 days is the appropriate response.
Bottom Line
Purulent nasal discharge does not indicate bacterial sinusitis — it is a normal part of viral URI. Antibiotics are indicated only for the three bacterial patterns: persistent ≥10 days, severe onset, or double worsening.
EVIDENCE & REFERENCES
- Chow AW, et al. IDSA clinical practice guideline for acute bacterial rhinosinusitis in children and adults. Clin Infect Dis. 2012;54(8):e72-e112. doi:10.1093/cid/cir1043
- Harris AM, et al. Appropriate antibiotic use for acute respiratory tract infection in adults. Ann Intern Med. 2016;164(6):425-434. doi:10.7326/M15-1840