Textbook of Urgent Care Medicine, Chapter 13, Sinusitis

Published on October 26, 2026

INTRODUCTION

Sinusitis is defined as inflammation of the paranasal sinuses. Because inflammation of the nasal cavity is almost always present as well, rhinosinusitis is the preferred modern term.

The most common predisposing factor for acute bacterial sinusitis (ABS) is a viral upper respiratory infection. Other underlying predisposing factors include allergic rhinitis, nasal airway obstruction, immunodeficiencies, ciliary dysfunction, and cystic fibrosis.

Most acute rhinosinusitis is viral. Bacterial disease should be diagnosed by the pattern and duration of illness rather than by mucus color or facial tenderness alone.

PRESENTATION

ABS presents with sinus pain and congestion. Purulent nasal drainage, nasal obstruction, and facial pain or pressure are common, but no single symptom distinguishes bacterial from viral disease. In adults, facial pain or pressure without purulent nasal drainage is insufficient to establish acute rhinosinusitis.

TRIAGE PEARLS

The presence of any of the following should prompt a more thorough evaluation for cavernous sinus thrombosis and other more threatening complications:

Orbital pain or swelling
Facial swelling
Meningeal signs
Mental status change
Cranial nerve palsy
Decreased visual acuity, diplopia or ophthalmoplegia, proptosis, severe frontal headache or forehead swelling, toxic appearance, or rapidly progressive facial/orbital findings should prompt emergency evaluation for orbital or intracranial extension.

HISTORY PEARLS

Ask the patient for details about having a history of any of the following:

Discolored nasal discharge (yellow, green, blood-streaked)
Cold symptoms that persist for at least 10 days without improvement, rather than simply lasting more than a week.
Pain behind the eyes or cheeks
Headache
Upper tooth pain
Ear congestion and/or pain
Symptoms were decreasing but are now worse again (“double-sickening”)
Facial redness, cellulitis overlying maxillary sinuses, periorbital cellulitis
Sore throat, postnasal drip, cough, and fever may be present, but their presence is not required for making a diagnosis.
Colored nasal discharge by itself does not establish bacterial infection; color change occurs commonly during viral upper respiratory infections.
In adults, diagnose presumed ABRS when purulent nasal drainage with nasal obstruction and/or facial pain-pressure persists without improvement for at least 10 days, or worsens after initial improvement.
In children, ABRS is diagnosed by persistent nasal discharge or daytime cough for at least 10 days without improvement, a worsening course after initial improvement, or severe onset with fever >=39 C (102.2 F) and purulent nasal discharge and/or facial pain for at least 3 consecutive days.

PHYSICAL EXAM PEARLS

Abnormal findings on inspection (facial or periorbital swelling)
Fever; in children, fever >=39 C with purulent nasal discharge for at least 3 days supports the severe-onset pattern of ABRS.
Tenderness over the sinuses
Reddening of nasal mucosa, cobblestone nasal mucosa (allergies), and purulent drainage from the sinus ostia
Transillumination is unreliable.
Exam findings may be normal even if sinusitis is present.
Sinus tenderness and purulent-appearing discharge are nonspecific and should not override the time course of illness when deciding whether disease is bacterial.
If orbital involvement is possible, document visual acuity, pupils, extraocular movements, proptosis, and periorbital findings.

TESTING PEARLS

Plain radiographs are no longer recommended as a tool for diagnosing uncomplicated sinusitis.
Do not obtain routine CT or MRI for uncomplicated acute rhinosinusitis. Imaging is reserved for suspected orbital/intracranial complication or an alternative diagnosis.
When orbital or intracranial extension is suspected, contrast-enhanced maxillofacial CT and/or MRI may be appropriate; MRI is especially useful for soft-tissue, orbital, or intracranial extension.
In adults with chronic rhinosinusitis, symptoms lasting more than 12 weeks should be confirmed with objective sinonasal inflammation by anterior rhinoscopy, nasal endoscopy, or CT rather than by symptoms alone.
Sinus aspiration or endoscopy-directed culture is not needed for routine uncomplicated ABRS. Consider culture through a specialist for complicated, unusual, or treatment-refractory disease.

DIAGNOSIS PEARLS

Complications include facial cellulitis, periorbital or orbital cellulitis, subperiosteal or orbital abscess, epidural or subdural empyema/brain abscess, cavernous sinus thrombosis, meningitis, and osteomyelitis including frontal bone osteomyelitis (Pott puffy tumor).
Adults: acute rhinosinusitis generally lasts less than 4 weeks. Chronic rhinosinusitis is defined by symptoms lasting more than 12 weeks and requires objective evidence of sinonasal inflammation.
Recurrent acute rhinosinusitis is 4 or more discrete episodes per year with no persistent symptoms between episodes. Repeated empiric antibiotic courses should not substitute for evaluation of the recurrent pattern.
Symptoms lasting 4 to 12 weeks fall between standard acute and chronic definitions and should be managed according to the clinical pattern and need for further evaluation rather than automatically labeled persistent bacterial sinusitis.

TREATMENT AND DISPOSITION PEARLS

Transfer any patients with suspected complications to the nearest emergency department.
Adults with uncomplicated ABRS should be offered watchful waiting without antibiotics when reliable follow-up is available. The 2025 AAO-HNSF guideline uses a 3- to 5-day observation period from diagnosis.
If an adult with uncomplicated ABRS is treated with an antibiotic, amoxicillin with or without clavulanate is first-line therapy for 5 to 7 days for most patients.
For adults with a true penicillin allergy, characterize the reaction and use age- and risk-appropriate alternatives. Doxycycline remains a CDC-listed alternative; the 2025 AAO-HNSF guideline removed respiratory fluoroquinolones as routine recommended agents for penicillin allergy.
In children with severe or worsening ABRS, prescribe antibiotics. For persistent illness without severe or worsening features, either prescribe antibiotics or observe for an additional 3 days with reliable follow-up.
Pediatric first-line therapy is amoxicillin or amoxicillin-clavulanate. High-dose amoxicillin-clavulanate is appropriate for severe disease or increased risk of resistant organisms. Current AAP Red Book guidance lists 5 to 7 days for acute sinusitis.
Macrolides and trimethoprim-sulfamethoxazole should not be used routinely for empiric ABRS because of resistance. Antibiotic selection should also account for local susceptibility patterns and the patient’s allergy history.
Analgesics, topical intranasal corticosteroids, and saline irrigation may be used for symptomatic relief of viral rhinosinusitis or ABRS.
Systemic corticosteroids are not routinely recommended for uncomplicated ABRS. Antihistamines and decongestants should not be used routinely for ABRS unless another indication, such as allergic rhinitis, is present; prolonged topical decongestant use risks rebound congestion.
Adults receiving antibiotics who worsen or fail to improve after 3 to 5 days should be reassessed to confirm ABRS, exclude another diagnosis, and look for complications before therapy is changed.
Children should be reassessed if they worsen at any time or fail to improve within 72 hours of observation or antibiotic therapy.
For chronic rhinosinusitis, saline nasal irrigation and topical intranasal corticosteroids are appropriate foundational therapy. Do not routinely prescribe antibiotics for CRS without an acute exacerbation.

CARE ALGORITHM

Figure 1. 2026 urgent-care algorithm for acute rhinosinusitis

1. Screen for complications. Proptosis, vision change, ophthalmoplegia/diplopia, marked orbital or facial swelling, cranial nerve deficit, severe frontal headache/swelling, meningismus, altered mental status, or toxic appearance -> emergency evaluation and complication-directed imaging.

2. Uncomplicated adult acute rhinosinusitis: purulent nasal drainage + nasal obstruction and/or facial pain-pressure. If <10 days and not worsening, manage as viral. If >=10 days without improvement or double worsening, diagnose presumed ABRS.

Adult ABRS: offer watchful waiting for 3-5 days with assured follow-up. If antibiotic is chosen, use amoxicillin with or without clavulanate for 5-7 days for most adults.

Pediatric ABRS: diagnose by persistent >=10-day illness, worsening after initial improvement, or severe onset (fever >=39 C + purulent drainage/facial pain for >=3 days). Severe/worsening -> antibiotics; persistent -> antibiotics or 3-day observation.

3. Reassess nonresponders: adults on antibiotics at 3-5 days; children within 72 hours. Confirm the diagnosis, look for complications or alternatives, and change therapy only if ABRS remains likely.

4. Chronic/recurrent disease: CRS >12 weeks or recurrent ARS >=4 episodes/year with symptom-free intervals warrants objective confirmation and specialty evaluation rather than repeated empiric antibiotic courses.

The original algorithm was adapted from the 2012 IDSA guideline. It was rebuilt for 2026 because adult watchful-waiting recommendations, treatment-failure timing, treatment duration, and the role of recurrent/chronic disease have changed.

MEDICOLEGAL PEARLS

Document a lack of signs consistent with cavernous sinus thrombosis or other orbital/intracranial complication when clinically relevant.
Document a lack of meningeal signs.
Document normal mental status.
When orbital symptoms are possible, document visual acuity, pupils, extraocular movements, proptosis, and facial/orbital swelling.
Document the clinical pattern used to diagnose ABRS (persistent >=10 days without improvement, double worsening, or the pediatric severe-onset pattern) rather than relying on mucus color alone.
If watchful waiting is chosen, document reliable follow-up and the specific time frame for reassessment or rescue antibiotic therapy.

REFERENCES

Payne SC, McKenna M, Buckley J, et al. Clinical Practice Guideline: Adult Sinusitis Update. Otolaryngol Head Neck Surg. 2025;173(Suppl 1):S1-S56. doi:10.1002/ohn.1344.
Payne SC, McKenna M, Buckley J, et al. Executive Summary of the Clinical Practice Guideline on Adult Sinusitis Update. Otolaryngol Head Neck Surg. 2025;173(2):299-316. doi:10.1002/ohn.1342.
Wald ER, Applegate KE, Bordley C, et al. Clinical Practice Guideline for the Diagnosis and Management of Acute Bacterial Sinusitis in Children Aged 1 to 18 Years. Pediatrics. 2013;132(1):e262-e280. doi:10.1542/peds.2013-1071.
American Academy of Pediatrics. Red Book: 2024-2027 Report of the Committee on Infectious Diseases. Systems-Based Treatment Table: Acute Sinusitis. American Academy of Pediatrics; 2024.
Abdel-Haq N. Sinusitis. Pediatric Care Online. American Academy of Pediatrics. Updated 2024.
Centers for Disease Control and Prevention. Outpatient Clinical Care for Adults: Acute Rhinosinusitis. Antibiotic Prescribing and Use. Accessed 2026.
Hagiwara M, Policeni B, Juliano AF, et al. ACR Appropriateness Criteria Sinonasal Disease: 2021 Update. J Am Coll Radiol. 2022;19(5 Suppl):S175-S193. doi:10.1016/j.jacr.2022.02.011.
Chow AW, Benninger MS, Brook I, 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.