Bacteria and viruses love this kind of closed-off space. However, even when sinusitis is due to infection, the cause is often a virus, not bacteria, so antibiotics still may not help.
It can be very hard to figure out if sinusitis is due to allergy or an infection, but the treatments are different, so it's important to try. Here are some of the clues:
- Time of year. If sinusitis happens around the same time or times every year, allergy is more likely.
- Environmental differences. If the symptoms are due to allergy, they may get better or worse as you move between different environments: indoors vs. outdoors; home vs. work; weekday vs. weekend; going away on vacation.
- Fever. A normal temperature or low grade fever (less than 100.5oF) is more likely to be allergy. Higher fevers are more consistent with viral or bacterial infection. However, chronic infections don't always cause fever, and the inflammation from allergies can cause fever.
- Mucus color. Clear or light colored mucus is more likely allergy and darker is more likely infection. However, color alone isn't enough information to make a diagnosis. It's also pretty common to have some streaks of blood in the mucus, due to the inflammation and frequent nose-blowing, regardless of the cause.
- Antibiotic failure. If one or more courses of antibiotics doesn't cure the problem, then allergy is much more likely.
- Coexisting conditions. People with asthma and/or eczema (a dry, scaly, itchy rash) are prone to developing allergies, too.
Infections often last from one to three weeks, while an allergic reaction will continue as long as the trigger is present. If over-the-counter remedies don't help you enough with your symptoms, or if you'd like increase the intensity of your treatment, then it's time to see your doctor for additional advice
