The most reliable sign of a sinus infection is cold-like symptoms that last 10 days or more without improving. A regular cold typically peaks around day three or four and then gradually gets better. If your congestion, facial pressure, and nasal discharge are still going strong after 10 days, or if they started to improve and then got worse again, you’re likely dealing with a sinus infection rather than a lingering cold.
The Three Patterns That Point to a Sinus Infection
Doctors use three specific patterns to distinguish a bacterial sinus infection from a viral cold. You only need to match one of them:
- The long haul: Symptoms persist for 10 or more days with no sign of improvement. Not just “still a little stuffy,” but actively sick with congestion, discharge, or facial pain that hasn’t budged.
- The severe start: You develop a fever of 102°F (39°C) or higher along with thick, discolored nasal discharge or significant facial pain, and these symptoms last at least three days from the very beginning of the illness.
- The double sickening: You get a cold, start feeling better around day five or six, then suddenly get worse again with a new fever, worsening headache, or increased nasal discharge. This rebound pattern strongly suggests a bacterial infection has developed on top of the original virus.
That “double sickening” pattern catches a lot of people off guard. You think you’re finally turning the corner, then wake up feeling worse than before. It happens because bacteria take advantage of the swollen, fluid-filled sinuses that a virus left behind.
What a Sinus Infection Feels Like
The hallmark symptoms are facial pressure or pain, thick nasal discharge, and congestion. But the details matter. The pressure typically concentrates in specific spots: across your cheekbones, around or above your eyes, or along the bridge of your nose. It often radiates into your upper teeth, which can make you think you have a dental problem.
One useful self-check: bend forward at the waist. If the pressure in your face noticeably increases when you lean down, that’s a classic sign of inflamed sinuses. The pain worsens because bending shifts fluid and increases pressure inside the sinus cavities. You can also press gently on the area just above the inner corner of your eye, near your eyebrow. Tenderness there suggests your frontal sinuses are involved.
Other common symptoms include a reduced sense of smell, post-nasal drip that causes a persistent cough (especially at night), fatigue, and bad breath. Some people also notice ear fullness or pressure, since the sinuses and ears share drainage pathways.
Why Mucus Color Doesn’t Tell You Much
Green or yellow mucus is one of the most common reasons people assume they need antibiotics. It’s also one of the most persistent myths in medicine. Both viral and bacterial infections change the color and thickness of nasal mucus. The greenish tint comes from enzymes released by your white blood cells as they fight any type of infection, viral or bacterial. A plain cold can produce bright green mucus for days. Meanwhile, a bacterial sinus infection doesn’t always produce discolored discharge at all.
So while thick, discolored mucus is part of the picture, it’s the duration and pattern of your symptoms that actually tell you whether bacteria are involved. Color alone is not a reliable indicator.
Sinus Infections in Children
Kids get colds far more often than adults, which makes it harder to spot when a cold has turned into a sinus infection. The key signal is the same as in adults: cold symptoms, particularly nasal discharge and daytime cough, that last more than 10 days without improving. Children are less likely to report facial pressure in specific terms, so parents typically notice the duration of symptoms rather than the location of pain. A child who seems to have a cold that simply won’t quit, especially with persistent cough and runny nose well past the 10-day mark, is a good candidate for evaluation.
When Symptoms Become Chronic
If your symptoms stretch beyond 12 weeks, the diagnosis shifts from acute to chronic sinusitis. Chronic sinusitis isn’t just a long cold. It involves ongoing inflammation in the sinuses that persists despite treatment, and it requires more than a symptom checklist to diagnose. Your doctor will typically need to confirm inflammation through a nasal endoscopy or a CT scan, because the symptoms of chronic sinusitis (congestion, facial pressure, reduced smell, post-nasal drip) overlap with allergies and other conditions.
Chronic sinusitis is a different condition with different management than an acute infection. If you’ve been dealing with sinus symptoms on and off for months, that distinction matters for getting the right treatment.
You Probably Don’t Need Imaging
Most people expect that diagnosing a sinus infection involves some kind of scan. It doesn’t. Medical guidelines specifically recommend against imaging for a straightforward sinus infection. A CT scan can’t reliably distinguish a bacterial sinus infection from a viral one, because both cause fluid buildup and swelling that look similar on a scan. X-rays perform even worse, with sensitivity as low as 25% for most sinus groups.
Imaging is reserved for situations where your doctor suspects a complication, such as an infection spreading toward the eye or brain, or when chronic sinusitis needs confirmation. For a typical case, diagnosis is based entirely on your symptoms and their timeline.
Red Flags That Need Immediate Attention
Sinus infections very rarely cause serious complications, but when they do, it’s because the infection has spread beyond the sinuses into nearby structures. Go to an emergency room if you experience any of the following alongside sinus symptoms:
- Swelling, redness, or pain around your eyes
- Double vision or other changes in your eyesight
- High fever that doesn’t respond to treatment
- Stiff neck
- Confusion or altered mental state
These symptoms suggest the infection may be affecting the eye socket or the central nervous system. They’re rare, but they require urgent evaluation. A CT scan with contrast or an MRI can detect these complications with high accuracy, reaching 91% and 97% respectively.