The hallmark signs of sinusitis are thick nasal discharge combined with either nasal congestion, facial pain or pressure, or both, lasting for several days or more. If you’re dealing with that combination of symptoms, especially after a cold, there’s a good chance your sinuses are inflamed. But telling sinusitis apart from a lingering cold or allergies takes a closer look at what you’re feeling and how long it’s been going on.
The Core Symptoms of Sinusitis
Sinusitis, technically called rhinosinusitis, is inflammation of the sinuses and nasal passages. The defining symptoms are purulent (thick, discolored) nasal discharge draining from the front of your nose or down the back of your throat, along with at least one of two other problems: nasal obstruction that makes it hard to breathe through your nose, or a feeling of pain, pressure, or fullness in your face.
Beyond those three core signs, you may also notice:
- Reduced sense of smell
- Pain in your upper teeth, particularly on one side
- Headache concentrated around your forehead, cheeks, or between your eyes
- Ear pressure or fullness
- Bad breath
- Fatigue
- Postnasal drip that triggers a cough, especially at night
Facial tenderness is one of the more telling signs. You can check this yourself by pressing gently over your cheekbones (where the maxillary sinuses sit) and above your eyebrows (the frontal sinuses). If that pressure produces a distinct ache, your sinuses are likely involved. Pain that’s noticeably worse on one side of your face is particularly suggestive.
Sinusitis vs. a Common Cold
Every sinus infection starts out looking like a regular cold, which is why timing matters so much. A typical cold improves within 7 to 10 days. Sinusitis is what happens when the inflammation sticks around or gets worse instead of resolving.
Three patterns suggest your cold has crossed into sinusitis territory. First, your symptoms persist beyond 10 days without meaningful improvement. Second, you experience “double worsening,” where you start to feel better, then your symptoms come back stronger. Third, your illness begins with a high fever and thick, discolored nasal discharge that lasts at least three consecutive days from the start. Any one of these patterns is a clinical marker for sinusitis rather than a simple cold.
Does Mucus Color Actually Matter?
You’ve probably heard that green or yellow mucus means you have a bacterial infection. The reality is more nuanced. While thick, discolored mucus does show a statistical correlation with bacterial infection, research published in the Scandinavian Journal of Primary Health Care found it’s actually a very weak diagnostic marker. The green color comes from an enzyme released by white blood cells as part of your normal immune response, which means viral infections can produce green mucus too.
In that study, using yellow or green mucus as a test for bacterial infection caught about 79% of actual bacterial cases but incorrectly flagged more than half of non-bacterial ones. The positive predictive value was just 16%, meaning that out of all the people with discolored mucus, only a small fraction actually had a bacterial infection. So while mucus color is one piece of the puzzle, it shouldn’t be the thing that convinces you that you need antibiotics.
Sinusitis vs. Allergies
Allergic rhinitis and sinusitis share several symptoms, including congestion and a runny nose, which makes them easy to confuse. The key differentiator is itching. Allergies typically cause itchy eyes, nose, and throat. Sinusitis does not. Frequent sneezing in bursts is also characteristic of allergies, while sinusitis may or may not involve sneezing.
Allergies also tend to follow a pattern tied to seasonal triggers or specific exposures like dust or pet dander. The discharge is usually thin and watery rather than thick. If your congestion came on after a cold, involves facial pain, and produces thick discharge, sinusitis is the more likely explanation. If it comes with itching, sneezing, and watery eyes, allergies are the better fit. That said, allergies can predispose you to sinus infections by causing the swelling that blocks normal sinus drainage.
Acute, Subacute, and Chronic Types
How long your symptoms last determines which category of sinusitis you’re dealing with, and that distinction affects what comes next.
- Acute sinusitis lasts fewer than 4 weeks. Most cases are viral and resolve on their own.
- Subacute sinusitis lasts between 4 and 12 weeks. This is a gray zone that often represents an acute infection that didn’t fully clear.
- Chronic sinusitis lasts more than 12 weeks. At this point, the issue is usually persistent inflammation rather than an active infection, and it typically requires a different treatment approach.
Recurrent acute sinusitis is another recognized pattern: four or more separate episodes per year, with symptom-free periods in between.
When a Viral Infection Becomes Bacterial
Most acute sinusitis cases are caused by viruses. Only a fraction develop into bacterial infections. The likelihood of a bacterial cause increases when your symptoms last seven days or more (especially with the double-worsening pattern), when your mucus is thick and yellow or green, when you have facial tenderness that’s worse on one side, or when you feel pain in your upper teeth on one side. None of these signs alone confirms bacteria, but the more of them you have, the stronger the case.
This distinction matters because antibiotics only help with bacterial sinusitis. Viral sinusitis, which accounts for the majority of cases, resolves with time and symptom management. Saline rinses, staying hydrated, and using a humidifier can help with either type.
How Sinusitis Is Diagnosed
For most people with a first or occasional sinus infection, the diagnosis is clinical, meaning it’s based on your symptoms and a physical exam rather than imaging or lab tests. A doctor will ask about the timeline of your symptoms, check for tenderness over your sinuses, and look inside your nose.
CT scans and nasal endoscopy (where a thin camera is passed into the nasal cavity) are reserved for specific situations. If your symptoms persist despite treatment, if chronic sinusitis is suspected, or if there’s concern about complications, imaging becomes useful. A CT scan is also a standard step before any sinus surgery. But for a straightforward acute episode, you won’t typically need any imaging. When endoscopy shows visible signs like pus, mucosal swelling, or polyps in the sinuses, that’s usually enough to confirm the diagnosis without a scan.
How Sinusitis Differs in Children
In older children and teenagers, sinusitis looks similar to the adult version, with headache and facial pressure as recognizable symptoms. In younger children, though, the signs are often vague and easy to miss. Instead of complaining about face pain, a young child with sinusitis might be unusually irritable, eat poorly, clear their throat frequently, have bad breath, or sound nasally. The same timing rules apply: symptoms lasting beyond 10 days without improvement, a high fever with thick discharge for three or more days, or the double-worsening pattern all point toward sinusitis rather than a lingering cold.
Red Flags That Need Immediate Attention
Sinusitis complications are rare, but when they happen, they can be serious because the sinuses sit close to the eyes and brain. Get emergency medical care if you notice any of the following alongside sinus symptoms:
- Vision changes, including blurred vision, double vision, or loss of vision
- Swelling or redness around the eye, especially if the eye appears to be pushed forward
- Pain or difficulty moving your eyes
- Severe headache that doesn’t respond to standard pain relief
- Stiff neck
- Confusion or changes in alertness
- Seizures
- Rapidly worsening symptoms despite treatment
These signs can indicate that the infection has spread beyond the sinuses into the eye socket or toward the brain. They’re uncommon, but they require urgent evaluation rather than a wait-and-see approach.