The most reliable sign of a sinus infection is symptoms that last longer than 10 days without improving, or symptoms that start getting better and then suddenly get worse again. A regular cold and a sinus infection share many of the same symptoms early on, so timing and a few key differences are what set them apart.
The 10-Day Rule
Most colds follow a predictable arc: you feel terrible for a few days, then gradually improve over a week or so. A sinus infection breaks that pattern in one of two ways. Either your symptoms persist beyond 10 days with no sign of improvement, or you start feeling better and then take a noticeable turn for the worse. Doctors call that second pattern “double worsening,” and it’s one of the most reliable indicators that a viral cold has progressed into a bacterial sinus infection.
This distinction matters because the vast majority of stuffy, miserable upper respiratory infections are caused by viruses that resolve on their own. Antibiotics won’t help a viral infection. The 10-day threshold is the standard that ear, nose, and throat specialists use to separate a lingering cold from something that needs treatment.
Symptoms That Point to a Sinus Infection
A cold and a sinus infection both cause congestion, a runny nose, and general fatigue. But sinus infections tend to produce a few symptoms that colds typically don’t, or at least not as intensely:
- Facial pressure or pain. You’ll feel it around your nose, behind your eyes, across your forehead, or in your cheeks. It often gets noticeably worse when you bend forward or tilt your head down.
- Thick, discolored nasal discharge. Yellow or green mucus is common with sinus infections, while colds usually produce thinner, clear drainage. That said, colored mucus alone isn’t proof of a bacterial infection. Viruses can also cause yellowish or greenish discharge, especially a few days into an illness.
- Tooth pain. Pressure or aching in your upper teeth, even though nothing is wrong with your teeth, happens because your maxillary sinuses sit right above the roots of your upper molars.
- Bad breath. Infected mucus draining down the back of your throat often has a foul smell. If you’re suddenly reaching for mints more often, your sinuses may be the cause.
- Reduced sense of smell. Swollen, inflamed sinuses block the airflow that carries scent molecules to your olfactory nerves.
The combination of facial pressure and discolored drainage is the most distinguishing pair of symptoms. Either one alone could happen with a cold, but together, especially after 10 days, they strongly suggest a bacterial sinus infection.
A Simple Self-Check
There’s no home test that definitively diagnoses a sinus infection, but you can gather useful information. Try leaning forward from the waist, as if you’re bending to tie your shoes. If you feel a distinct increase in pressure or throbbing pain around your eyes, forehead, or cheeks, that’s a sign your sinuses are inflamed and possibly infected. You can also press gently on the areas just above your eyebrows and on both sides of your nose, along your cheekbones. Tenderness in those spots corresponds to the frontal and maxillary sinuses, the two most commonly affected.
What Mucus Color Actually Tells You
Green or yellow mucus is widely assumed to mean a bacterial infection, but this is an oversimplification. Both viral and bacterial infections change mucus color. What matters more is the timing. With a virus, mucus typically starts clear, turns colored around days three through five, and then clears up. With a bacterial infection, thick, colored mucus tends to appear early and persist past the 10-day mark without improving. So the color itself is less important than how long it lasts and whether the rest of your symptoms are following a normal cold timeline.
Sinus Infections in Children
Kids get sinus infections too, but they’re harder to spot because young children can’t always describe facial pressure or headache pain. In children, the key signs include a cough and nasal discharge lasting more than 10 days with no improvement, thick yellow discharge paired with a fever persisting three or four days, and swelling or dark circles around the eyes (especially in the morning). Persistent bad breath alongside cold symptoms is another common clue in kids, though it can also stem from a sore throat or inconsistent tooth brushing. Unusual irritability in a young child who also has prolonged cold symptoms is worth paying attention to.
When a Sinus Infection Becomes Chronic
Most sinus infections are acute, meaning they develop quickly and clear up within a few weeks with or without treatment. But when symptoms persist for 12 weeks or longer, even with treatment, the condition is classified as chronic sinusitis. Chronic sinusitis involves the same core symptoms (congestion, facial pressure, discolored drainage, reduced smell) but at a lower, grinding intensity that doesn’t fully resolve. The causes are often different too: nasal polyps, a deviated septum, or ongoing inflammation rather than a single bacterial infection. If you’ve had repeated sinus infections or symptoms that never quite go away, that 12-week threshold is the line your doctor will use to shift the approach.
How Doctors Confirm It
Most sinus infections are diagnosed based on your symptoms and a physical exam. Your doctor will ask how long you’ve been sick, whether symptoms improved and then worsened, and what your discharge looks like. They may look inside your nose with a light to check for swelling and drainage.
If your symptoms keep coming back or don’t respond to treatment, a specialist may use a nasal endoscopy, a thin, flexible tube with a camera that lets them see directly into your sinus passages. This helps identify structural problems, polyps, or persistent inflammation that wouldn’t be visible otherwise. A CT scan is sometimes ordered when even more detail is needed to plan treatment.
Signs That Need Immediate Attention
Sinus infections rarely cause serious complications, but in uncommon cases, the infection can spread to nearby structures. Swelling or redness around one eye, pain when moving your eyes, changes in vision, or an eye that appears to be bulging forward are signs that infection may have reached the tissue around the eye socket. A high fever, severe headache, or unusual drowsiness alongside sinus symptoms can indicate the infection is spreading toward the brain. These situations require emergency care, not a wait-and-see approach. In children especially, rapid swelling around the eye or sudden high fever with sinus symptoms warrants an immediate call to their doctor.