A sinus infection typically shows up as swelling and redness around the nose, cheeks, or eyes, often with thick yellow or green mucus draining from the nose or down the back of the throat. Some people notice puffiness around the eye sockets, while others mainly see the infection in what comes out of their nose. What a sinus infection looks like depends on whether you’re checking your own face in the mirror, looking at your nasal discharge, or seeing the results of a medical exam or scan.
What You Can See on Your Face
The most obvious external signs of a sinus infection are redness and swelling. Your nose, cheeks, or eyelids may look flushed or puffy, especially on the side where the infection is worst. Swelling around the eyes, called periorbital edema, is common because the sinuses sit directly behind and above the eye sockets. In some cases, the skin over the affected sinus feels warm to the touch and looks visibly inflamed compared to the surrounding area.
These visible changes tend to be more dramatic in acute infections than chronic ones. A mild sinus infection might not change your appearance much at all, while a severe one can make you look noticeably swollen and exhausted. Children in particular can develop pronounced puffiness around the eyes that parents sometimes mistake for an allergic reaction.
What Your Nasal Discharge Tells You
Mucus color is the first thing most people check when they suspect a sinus infection, and the picture is more complicated than you might expect. Thick, yellowish or greenish-gray discharge is a hallmark of sinusitis, but green mucus alone does not confirm a bacterial infection. Both viral and bacterial infections cause similar changes in mucus color. The color shift happens because your immune cells flood the area and release enzymes, not necessarily because bacteria are present.
The timing of the color change matters more than the color itself. During a regular cold, mucus starts watery and clear, then gradually thickens and turns yellow or green over several days. With a bacterial sinus infection, thick colored mucus more often appears at the beginning of the illness rather than building up slowly. If your symptoms improve and then suddenly get worse again, that “double worsening” pattern is a stronger signal of bacterial infection than mucus color alone. Bacterial infections also tend to last more than 10 days without any improvement, while viral colds typically start getting better before that point.
You may also notice purulent discharge dripping down the back of your throat, visible as a thick, opaque coating on the back of the throat if you look in a mirror with a flashlight. This post-nasal drip often causes a persistent cough, particularly at night.
How It Looks in Children
Sinus infections in kids can look different from adults. Children are less likely to complain about facial pressure and more likely to show indirect signs. A persistent cough that worsens at night is one of the most reliable visible clues. Bad breath that doesn’t improve with brushing is another telltale sign, caused by infected mucus pooling in the back of the throat and nasal passages. Parents often notice the smell before any other symptom. Combined with a runny nose that has lasted well over a week, these signs together paint a clearer picture than any single symptom.
What a Doctor Sees During an Exam
When a clinician looks inside your nose with a light or a thin flexible camera called an endoscope, the picture becomes much more specific. Healthy nasal tissue is pink and moist. Infected sinuses produce visible swelling of the nasal lining, which looks red and boggy. The key finding is pus draining from the sinus openings, particularly from the middle meatus, a small passage on the side wall of the nasal cavity where several sinuses drain. A doctor can sometimes collect this pus directly for testing.
In chronic or recurrent infections, the endoscope may also reveal nasal polyps: smooth, pale, grape-like growths that hang from the sinus lining and block normal drainage. Polyps are not the infection itself, but they create the conditions for infections to keep coming back by trapping mucus inside the sinuses.
What a Sinus Infection Looks Like on a CT Scan
If your doctor orders imaging, a CT scan reveals the infection in striking detail. Healthy sinuses appear as dark, air-filled spaces. Infected sinuses show several characteristic patterns: fluid levels visible as a sharp horizontal line inside the sinus cavity (like a glass half-full of water), thickened lining along the sinus walls, air bubbles trapped within fluid, or complete opacification where the entire sinus appears white instead of dark because it’s completely filled with mucus or pus.
One important caveat: sinus abnormalities on CT scans are surprisingly common even in people without symptoms. Studies have found that up to 42.5% of people scanned for unrelated reasons (like migraines) show some sinus abnormality. This is why doctors diagnose sinus infections based on your symptoms and exam findings, not imaging alone. A CT scan is most useful for chronic cases or when complications are suspected.
Warning Signs That Need Emergency Attention
In rare cases, a sinus infection can spread beyond the sinuses into the eye socket or surrounding tissue. This is most common in children and produces dramatic, unmistakable visual changes. A bulging eye, severe swelling of the eyelid and skin around the eye, redness or discoloration spreading across the eye area, difficulty moving the eye, double vision, or impaired vision all signal a condition called orbital cellulitis. The infection has essentially broken through the thin bone between the sinus and the eye socket.
A high fever combined with any of these eye symptoms, especially in a child, requires an emergency room visit. Orbital cellulitis can damage vision permanently if not treated quickly. Swelling can paralyze the muscles that control eye movement, causing the eye to become misaligned. This complication is uncommon, but it’s the reason doctors take sinus infections that are worsening or not responding to treatment seriously.