A sinus infection typically announces itself with three hallmark symptoms: thick, discolored nasal discharge, nasal congestion, and pain or pressure in your face. Most sinus infections start as ordinary colds, so the real question isn’t whether your nose is stuffed up, but whether your symptoms have crossed a line that separates a regular cold from something more. The key marker is time: symptoms that persist without improvement for at least 10 days, or symptoms that get worse after initially getting better.
The Three Core Symptoms
A sinus infection, also called sinusitis, produces a specific cluster of symptoms that overlap with colds and allergies but tend to be more intense and more localized. The combination doctors look for is purulent (thick, cloudy, or discolored) nasal drainage alongside nasal obstruction, facial pain or pressure, or both.
Facial pressure tends to concentrate in predictable spots depending on which sinuses are affected. If your maxillary sinuses (behind your cheeks) are involved, you’ll feel pain over the cheek area that can radiate up toward your forehead or down into your upper teeth. Frontal sinus involvement produces tenderness just above the inner corner of your eye, near the bridge of the nose. This pressure often gets noticeably worse when you bend forward or strain.
Other symptoms that commonly show up alongside the big three include a reduced sense of smell, postnasal drip (mucus draining down the back of your throat), ear fullness, headache, bad breath, fatigue, and a cough that tends to be worse at night.
The 10-Day Rule
Here’s what most people don’t realize: the vast majority of sinus infections are caused by viruses, not bacteria. A viral sinus infection is essentially a bad cold that has inflamed your sinus passages, and it will resolve on its own. Antibiotics won’t help.
The timeline is your best diagnostic tool. According to guidelines from the American Academy of Otolaryngology, a bacterial sinus infection is likely when your symptoms persist without any improvement for at least 10 days after they started. Before that point, you’re almost certainly dealing with a viral infection or a cold.
There’s a second pattern to watch for, sometimes called “double sickening.” This is when you start to feel better after a few days, then your symptoms suddenly worsen again within the first 10 days. That rebound suggests bacteria have taken hold in sinuses that were already inflamed from a virus. A new fever appearing after initial improvement, or facial pain that intensifies after a period of relief, are classic signs of this pattern.
Mucus Color Is Not What You Think
Green or yellow mucus is widely believed to signal a bacterial infection, but this is a myth, even among some healthcare providers. Both viral and bacterial infections cause similar changes in mucus color. The greenish or yellowish tint comes from immune cells and their enzymes flooding the area to fight infection, regardless of whether the invader is a virus or bacteria. So while thick, discolored discharge is one feature of sinusitis, its color alone cannot tell you whether you need antibiotics.
Sinus Infection vs. Allergies
Allergies and sinus infections share congestion, pressure, and runny nose, which makes them easy to confuse. The simplest way to tell them apart: itchy, watery eyes point strongly toward allergies. Itchiness is rarely a symptom of a sinus infection. Allergies also tend to produce clear, thin, watery discharge rather than thick and cloudy mucus.
Allergies follow patterns tied to triggers. If your symptoms flare up seasonally, worsen outdoors, or improve when you leave a particular environment, allergies are the more likely cause. Sinus infections, by contrast, typically follow a cold and get progressively worse over days before they plateau or improve. Fever can accompany a sinus infection but is not a feature of allergies.
When It Lasts Longer Than 12 Weeks
Acute sinusitis typically clears within 10 days to four weeks. If your symptoms drag on for 12 weeks or more, you’ve crossed into chronic sinusitis territory. Chronic sinusitis doesn’t always feel as intense as an acute infection. Instead, you might have a persistent low-grade stuffiness, reduced sense of smell, ongoing postnasal drip, and a general heaviness in your face that becomes your new normal.
Chronic sinusitis has different underlying causes than a one-time infection. Nasal polyps, a deviated septum, allergies, or an immune system issue can keep your sinuses inflamed long after any initial infection has cleared. Treatment looks different too, often focusing on reducing inflammation rather than fighting bacteria.
Symptoms in Children
Children get sinus infections but often show them differently than adults. A child with sinusitis will commonly have a persistent cough, yellow or green nasal discharge, nasal congestion that causes mouth breathing or snoring, headache, and facial pain or pressure. Fever is more commonly associated with acute sinusitis in children than in adults. Because young children can’t easily describe facial pressure, persistent congestion with a cough lasting beyond 10 days is often the most useful clue.
Signs That Need Prompt Attention
Most sinus infections resolve with time and symptom management. But in rare cases, the infection can spread beyond the sinuses into nearby structures, including the eyes, brain, or spinal cord. Symptoms that warrant urgent evaluation include a high fever (above 102°F or 39°C), severe headache that doesn’t respond to pain relievers, swelling or redness around your eyes, vision changes like double vision or difficulty seeing, a stiff neck, or confusion. These are uncommon, but they represent situations where a sinus infection has moved beyond the sinuses themselves.