A sinus infection is likely when you’ve had cloudy or colored nasal discharge for several days along with facial pressure, congestion, or both. The key distinction from a regular cold is the timeline: most colds improve within 7 to 10 days, while a sinus infection either persists beyond that window or follows a pattern of getting better then suddenly getting worse again.
The Core Symptoms
Three symptoms define a sinus infection. First, thick yellow or greenish mucus, either draining from your nose or running down the back of your throat (postnasal drip). Second, a stuffy or blocked nose that makes breathing through it difficult. Third, pain, pressure, or tenderness around your eyes, cheeks, nose, or forehead that gets worse when you bend over. You need the discolored mucus plus at least one of the other two to meet the clinical definition of acute sinusitis.
Other common symptoms include a reduced sense of smell, ear pressure, headache, bad breath, fatigue, and a cough that worsens at night. Fever can occur but isn’t always present.
Where the Pain Points to the Problem
Your face has four pairs of sinus cavities, and the location of your pain can tell you which ones are inflamed. Forehead pain points to the frontal sinuses. Pain in your cheekbones or upper teeth suggests the maxillary sinuses, the largest pair, sitting just below your eyes. Pressure at the bridge of your nose involves the ethmoid sinuses, and pain behind your eyes or in your ears signals the sphenoid sinuses deeper in your skull. Many people have inflammation in more than one set at a time, which is why the discomfort can feel diffuse and hard to pin down.
Cold, Allergies, or Sinus Infection
The overlap between a cold and a sinus infection is enormous in the first few days, because most sinus infections actually start as colds. The virus inflames and swells the sinus lining, trapping mucus, and sometimes bacteria move in and set up a secondary infection. So the early symptoms are essentially identical.
Timeline is your most reliable tool. A typical cold peaks around days 3 to 5 and then steadily improves. If your symptoms persist for 10 days without any improvement, that pattern suggests a bacterial sinus infection rather than a lingering virus. There’s also a “double worsening” pattern to watch for: you start feeling better around days 4 to 7, then your symptoms suddenly spike again with new facial pain or a fresh wave of congestion and fever. That rebound strongly suggests bacteria have taken hold.
Allergies, by contrast, tend to cause clear (not colored) discharge, itchy eyes, and sneezing. They follow environmental triggers rather than a timeline of illness, and they don’t cause fever.
Green Mucus Doesn’t Mean Bacterial
One of the most persistent misconceptions is that yellow or green mucus automatically means you need antibiotics. It doesn’t. When your immune system fights any irritant, whether viral, bacterial, or even an allergen, white blood cells release iron-containing enzymes that tint the mucus green. Mucus that sits in your sinuses while you sleep becomes more concentrated and darker. This happens with every cold, not just bacterial infections. Most sinus infections are viral and resolve on their own. You can’t reliably distinguish a viral from a bacterial sinus infection based on mucus color alone.
When Symptoms Suggest Something Bacterial
Three patterns point toward a bacterial sinus infection that may benefit from antibiotics, according to guidelines from the CDC and the Infectious Diseases Society of America:
- Persistent symptoms: nasal congestion, discharge, and facial pain lasting 10 or more days without improvement.
- Severe onset: a fever of 102°F (39°C) or higher with facial pain and purulent nasal discharge lasting 3 to 4 consecutive days.
- Double worsening: symptoms that improve after 4 to 7 days and then noticeably worsen again.
If none of these patterns apply, the infection is most likely viral. Viral sinus infections, while miserable, clear up with time, rest, and symptom management like saline rinses, steam, and pain relievers.
You Probably Don’t Need a CT Scan
If you’re wondering whether you need imaging to confirm a sinus infection, the answer for most cases is no. Medical guidelines from the American Academy of Otolaryngology specifically recommend against CT scans or X-rays for uncomplicated acute sinusitis. Your doctor can diagnose it based on your symptoms and their duration. Imaging is reserved for situations where a complication is suspected or when symptoms drag on for more than 12 weeks, at which point inflammation needs to be visually confirmed to diagnose chronic sinusitis.
How Sinus Infections Look Different in Children
Children get sinus infections too, but their symptoms don’t always match the adult pattern. Kids are less likely to report facial pressure and more likely to have a persistent cough, especially during the day. The same 10-day rule applies: if a child has nasal discharge and a cough that last more than 10 days without improving, that’s the signal. In younger children, irritability and low-grade fever may be the most obvious signs. Some pediatricians will observe for a few additional days before starting treatment if the child isn’t worsening.
Symptoms That Need Immediate Attention
Sinus infections occasionally spread beyond the sinuses, particularly in adolescents and young adults with frontal sinus involvement. The sinuses sit close to the eyes and brain, and infection can migrate to these areas. Eye swelling, bulging, blurry vision, or pain with eye movement are signs of orbital involvement, which typically requires more than antibiotics alone. Severe headache with high fever, stiff neck, or confusion can signal that infection has reached the brain lining. A teenager with frontal headache and even a low-grade fever warrants careful evaluation, because intracranial complications in this age group can be easy to miss early.
These complications are uncommon, but they escalate quickly. Double vision, a swollen or protruding eye, or a sudden change in how clearly you can see are reasons to get evaluated the same day rather than waiting to see how things develop.