Most sinus infections clear up within 7 to 10 days without any treatment. Some linger for up to four weeks, and a smaller number become chronic problems lasting 12 weeks or longer. How long yours lasts depends largely on whether a virus or bacteria is behind it, and whether inflammation has become self-sustaining even after the original infection is gone.
Acute Sinus Infections: 1 to 4 Weeks
The vast majority of sinus infections are viral, meaning they behave like a bad cold that settles into your sinuses. Symptoms like congestion, facial pressure, thick nasal discharge, and a reduced sense of smell typically last 7 to 10 days and go away on their own. Some people experience symptoms that stretch closer to four weeks, which still falls within the “acute” category.
A smaller percentage of acute infections are bacterial. Bacteria tend to move in after a virus has already inflamed the sinus lining, creating a warm, blocked environment where bacteria thrive. Bacterial sinus infections don’t necessarily last longer on their own. In clinical trials comparing antibiotics to placebo, the average illness duration was about six days in both groups. The difference is that bacterial infections carry a higher risk of complications, which is why antibiotics are sometimes prescribed.
How to Tell If It’s Bacterial
Since most sinus infections are viral, the key question is whether yours has crossed the line into bacterial territory. The CDC uses three patterns to make this call:
- The 10-day rule: Symptoms that persist for 10 days with no improvement at all are likely bacterial.
- Severe onset: A fever of 102°F or higher combined with facial pain and thick nasal discharge lasting 3 to 4 days suggests bacteria from the start.
- Double worsening: Symptoms that seem to improve after 4 to 7 days, then suddenly get worse again, point to a bacterial infection that has taken hold after the initial virus.
If none of these patterns apply, your body is almost certainly fighting off a virus, and antibiotics won’t help.
Subacute Infections: 4 to 12 Weeks
When a sinus infection drags on past four weeks but resolves before the 12-week mark, it falls into the subacute category. This is less common than a straightforward acute infection and often represents a bacterial infection that wasn’t fully cleared, or ongoing inflammation from allergies or anatomical issues like a deviated septum that keeps the sinuses from draining properly. Subacute infections generally do resolve, but they’re more likely to need treatment to get there.
Chronic Sinusitis: 12 Weeks or More
Chronic sinusitis is defined by at least two of four core symptoms persisting for 12 consecutive weeks or longer: facial pain or pressure, reduced or lost sense of smell, nasal drainage, and nasal obstruction. A diagnosis also requires objective evidence of inflammation, typically from a nasal exam or CT scan.
The important distinction is that chronic sinusitis is usually driven by persistent inflammation rather than an active, ongoing infection. The sinus lining stays swollen and irritated long after the original trigger is gone. Nasal polyps, allergies, asthma, and immune system issues all increase the risk. Because the underlying problem is inflammation rather than infection, treatment focuses on reducing swelling (often with steroid nasal sprays or rinses) rather than killing bacteria.
Chronic sinusitis can last months or years if left unmanaged. For some people it becomes a recurring condition that flares and subsides rather than something that fully resolves once.
Why Symptoms Linger After the Infection Clears
Even after a sinus infection is truly gone, you may notice a lingering cough or post-nasal drip for weeks afterward. This post-viral cough happens because the infection ramped up mucus production and irritated your airways, and that irritation doesn’t switch off the moment the virus dies. A persistent cough can last 3 to 8 weeks after the infection. A cough lasting beyond 8 weeks is considered chronic and worth investigating further.
This lingering phase doesn’t mean you’re still sick. It means your airways are still healing. The excess mucus your body produced during the infection takes time to clear, and the inflamed tissue in your sinuses and throat needs time to calm down.
What Helps You Recover Faster
For a standard viral sinus infection, the most effective approach is keeping your sinuses draining. Saline nasal rinses flush out mucus and reduce the bacterial load in your nasal passages. Steam, warm compresses over your face, and staying well-hydrated all help thin mucus so it moves out more easily.
Over-the-counter decongestant sprays can provide quick relief, but they come with an important limit. The UK’s drug regulator issued guidance that nasal sprays containing common decongestant ingredients should not be used for more than five consecutive days. Longer use can cause rebound congestion, where the spray itself starts making your nasal passages swell. This can spiral into a chronic congestion problem called rhinitis medicamentosa that’s harder to treat than the original infection.
Oral decongestants and pain relievers can help manage symptoms while your immune system does the work. If your infection meets the criteria for bacterial sinusitis, antibiotics can speed recovery, though the benefit is modest. In studies, about 80% of patients on antibiotics recovered within 14 days compared to 66% on placebo, and the antibiotic group experienced more side effects.
Sinus Infections in Children
Children follow similar timelines, but the diagnostic clues differ slightly. A child sick for fewer than 10 days whose symptoms aren’t worsening almost certainly has a viral infection. The same 10-day rule applies for suspecting a bacterial cause: if a child shows no improvement after 10 days, or gets worse after initially improving, bacteria are the likely culprit. Chronic sinusitis in children uses the same 12-week threshold as adults and is typically caused by prolonged inflammation rather than a persistent infection.
Signs That Need Immediate Attention
Sinus infections very rarely cause serious complications, but when they do, the sinuses’ proximity to the eyes and brain is the concern. Swelling, redness, or pain around the eye, especially if it affects vision or makes it hard to move the eye, can signal that the infection has spread to the tissue surrounding the eye socket. High fever paired with a severe, worsening headache is another red flag. These complications require urgent treatment and should not be managed at home.