Sinusitis: Acute and Chronic, and Why Most Cases Don't Need Antibiotics

In short

Sinusitis means inflammation of the sinuses, and most short-lived cases are caused by viruses that antibiotics can't touch — understanding the difference between acute and chronic sinusitis helps set realistic expectations for treatment.

Emergency if: Swelling or redness around the eye, an eye that bulges or does not move normally, double vision or new blurred vision, a severe headache, swelling over the forehead, a stiff neck, confusion, or weakness on one side of the body alongside sinus symptoms: go to an emergency department now. NICE says these signs of infection spreading to the eye socket or brain need hospital care.

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What Sinusitis Is

Sinusitis is inflammation or swelling of the tissue lining the sinuses, the air-filled spaces around the nose and eyes, which leads to symptoms such as facial pain or pressure, nasal congestion, thick nasal discharge, and reduced sense of smell. It's frequently triggered by a viral upper respiratory infection, though allergies and structural issues in the nose can also contribute.

Sinusitis is described as acute when symptoms last under four weeks, and chronic when they persist for twelve weeks or longer, a distinction that meaningfully changes both the likely cause and the treatment approach.

Viral Versus Bacterial: Why Antibiotics Aren't Always the Answer

The large majority of acute sinusitis cases are caused by viruses, which antibiotics have no effect on, and most get better on their own with supportive care: NICE gives the usual course as 2 to 3 weeks, and the NHS says sinusitis usually clears up within 4 weeks. Using antibiotics for a viral infection doesn't speed recovery and contributes to antibiotic resistance over time.

A bacterial sinus infection is more likely when symptoms are severe, last beyond ten days without improving, or improve initially and then clearly worsen again. Doctors weigh this pattern, rather than symptoms alone on day one or two, before deciding whether antibiotics are appropriate.

Chronic Sinusitis Is a Different Problem

Chronic sinusitis, lasting twelve weeks or more, is less often about a single infection and more often related to ongoing inflammation, allergies, nasal polyps, or structural issues that block normal sinus drainage. It typically needs a different diagnostic approach, often including a nasal endoscopy or CT scan of the sinuses.

Because the underlying driver differs from a simple infection, chronic sinusitis usually responds better to treatments aimed at reducing inflammation and improving drainage rather than repeated courses of antibiotics.

The Treatment Landscape

For acute viral sinusitis, supportive care such as saline nasal rinses, decongestants, and pain relief is the main approach while the body clears the infection on its own. NICE says there is not enough evidence that nasal decongestants help, and MedlinePlus warns that using a decongestant nasal spray for more than 3 to 5 days can make stuffiness worse. When bacterial infection is confirmed or strongly suspected, a course of antibiotics may be prescribed.

For chronic sinusitis, nasal corticosteroid sprays, saline irrigation, and treatment of underlying allergies are typically first steps. When these aren't enough, an ear, nose, and throat specialist may recommend further evaluation and, for structural blockages or polyps, a surgical procedure to improve drainage.

When to See an ENT Specialist

Most acute sinusitis can be managed by a primary care doctor, but recurrent episodes, symptoms lasting beyond twelve weeks, or sinusitis that isn't responding to standard treatment warrant referral to an ear, nose, and throat specialist for a closer look at underlying causes.

Swelling or redness around the eye, double vision or any new change in vision, a severe headache, swelling over the forehead, a stiff neck or confusion alongside sinus symptoms can mean the infection has spread beyond the sinuses: go to an emergency department now. A high fever, feeling very unwell, or symptoms that keep getting worse despite pain relief need a doctor today.

Sinus symptoms: how fast to act

Routine — see a doctor

No improvement after 3 weeks of self-care, sinusitis that keeps coming back, or symptoms lasting 12 weeks or more: book a visit with a doctor.

Same-day — call promptly

You feel very unwell or have a high fever, painkillers do not help or symptoms are getting worse, or you have a weakened immune system, for example during chemotherapy: see a doctor today. The NHS lists these as reasons for urgent advice.

Emergency — act now

Swelling or redness around the eye, an eye that bulges or does not move normally, double vision or new blurred vision, a severe headache, swelling over the forehead, a stiff neck, confusion, or weakness on one side of the body alongside sinus symptoms: go to an emergency department now. NICE says these signs of infection spreading to the eye socket or brain need hospital care.

Sources

Sinusitismedlineplus.gov
Sinusitis (acute): antimicrobial prescribing — NICEnice.org.uk
Sinusitis (sinus infection) — NHSnhs.uk
Sinusitis — MedlinePlus Medical Encyclopediamedlineplus.gov

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