A nasal infection, commonly called sinusitis or a sinus infection, shows up as a combination of congestion, facial pressure, and thick nasal discharge lasting longer than you’d expect from a typical cold. Around 90 to 98 percent of cases start as viral infections that resolve on their own, so the real question isn’t just whether you have one, but whether it’s something that needs treatment.
The Core Symptoms to Look For
Doctors use a specific checklist to diagnose a sinus infection. The major symptoms are thick or discolored nasal discharge, nasal congestion or obstruction, facial pain or pressure, a feeling of fullness in the face, a reduced sense of smell, and fever. You’d typically need at least two of these to point toward sinusitis rather than a simple cold or allergies.
There’s also a set of less obvious symptoms that can accompany the main ones: headache, ear pain or fullness, bad breath, tooth pain (especially in your upper teeth), cough, and fatigue. On their own, these don’t confirm a sinus infection, but paired with one or more major symptoms, they strengthen the picture. Tooth pain in particular is worth paying attention to. Your upper teeth sit right below your maxillary sinuses, and pressure from swollen, infected sinuses can radiate downward in a way that feels remarkably like a dental problem.
Is It a Cold, Allergies, or a Sinus Infection?
A regular cold and a sinus infection can feel nearly identical in the first few days. Both cause congestion, runny nose, and general misery. The difference shows up in how long symptoms last and how they progress. A cold typically peaks around days three to five and clears up within seven to ten days. A sinus infection lingers, often getting worse instead of better after that first week.
Allergies share some symptoms with sinusitis, particularly congestion and a runny nose, but they come with their own signature: sneezing, itchy nose, and itchy or watery eyes. Allergies don’t cause fever. If you’re experiencing facial pain or pressure along with greenish-yellow discharge and no itchiness or sneezing, that pattern fits sinusitis much better than allergies. That said, recurring allergies can lead to sinus infections over time by keeping the sinuses inflamed and blocking normal drainage.
Viral vs. Bacterial: When It Actually Matters
Here’s the part most people get wrong: the color of your mucus doesn’t reliably tell you whether the infection is bacterial. Green or yellow discharge is one of the most persistent myths in medicine. Both viral and bacterial infections cause the same changes in mucus color. The discoloration comes from immune cells your body sends to fight the infection, not from bacteria themselves. During a common cold, mucus often starts clear and watery, then becomes thicker and yellow or green as your immune system ramps up. That shift is completely normal and not a reason to ask for antibiotics.
The real markers that suggest a bacterial sinus infection are more about timing and severity:
- The 10-day rule. Symptoms like congestion, facial pain, and thick discharge that persist for more than 10 days without improvement suggest bacteria have moved in.
- The double-sickening pattern. You start getting better after a cold, then suddenly worsen again with new or returning symptoms after seven or more days. This rebound often signals a secondary bacterial infection.
- Severe onset. A fever above 102°F with facial pain on one side and thick discharge lasting three or more days points toward bacteria from the start.
One symptom that’s surprisingly useful is detecting a foul smell in your nose that isn’t coming from your surroundings. This sensation nearly doubles the likelihood that a bacterial infection is present. Pain in the upper teeth also nudges the odds toward a bacterial cause.
Most cases improve within two weeks regardless of whether antibiotics are involved. Antibiotics only help when there’s genuine evidence of bacterial infection, and even then, they shorten the illness rather than cure something your body couldn’t handle alone.
Acute vs. Chronic Sinusitis
An acute sinus infection is one that lasts less than four weeks. Most people deal with this type, and it usually resolves within 10 to 14 days. If your symptoms stretch past 12 weeks, that crosses into chronic sinusitis, which is a different condition with different underlying causes. Chronic sinusitis often involves persistent low-grade inflammation, nasal polyps, or structural issues rather than an active infection. It tends to feel less intense day to day but grinds on with ongoing congestion, reduced smell, facial pressure, and fatigue that doesn’t let up for months.
What a Doctor’s Evaluation Looks Like
If you do see a provider, the evaluation is straightforward. They’ll ask about how long your symptoms have lasted, whether they’ve improved or worsened, and what specifically you’re feeling. A physical exam involves pressing on your face and forehead to check for tenderness over the sinuses and looking inside your nose.
If chronic sinusitis is suspected, or if symptoms keep returning, you may be referred to an ear, nose, and throat specialist who can use nasal endoscopy. This involves inserting a thin, flexible tube with a light into your nose to get a direct view of the sinus openings. The provider looks for swelling, blockages, or thick drainage coming from the sinus passages. Imaging like a CT scan is reserved for complicated or chronic cases, not for a routine acute infection.
Symptoms That Need Immediate Attention
Sinus infections very rarely cause serious complications, but when they do, the infection has typically spread beyond the sinuses into nearby structures like the eye socket or the tissue surrounding the brain. Go to an emergency room if you develop swelling or redness around your eyes, double vision or other visual changes, a high fever that won’t come down, a stiff neck, or confusion. These symptoms can signal an orbital infection or, in rare cases, meningitis, both of which require urgent treatment.