April 12, 2013
Dear Mayo Clinic:
I have long suffered from allergies. But there have been times when I haven't been sure if my symptoms are really from my allergies or may be caused by a sinus infection instead. How can I tell the difference?
Allergies and sinus infections are often mistaken for one another. But they are two separate conditions. By paying close attention to the specific symptoms you have, you can usually identify which one is more likely to be causing the problem.
A sinus infection, also called sinusitis, affects the cavities around your nasal passages. The infection causes your sinuses to become inflamed and swollen. The swelling makes it hard for your sinuses to drain, and mucus builds up. You become congested and have trouble breathing through your nose. Sinusitis often causes thick yellow or green nasal discharge. A sore throat, cough or headache, as well as pressure or tenderness around your eyes, cheeks, nose or forehead, may also accompany sinusitis.
In most cases, viruses cause sinusitis. These viral infections usually go away on their own within a week to 10 days. Self-care measures such as extra rest and fluids along with over-the-counter pain relievers and decongestants can help. When sinusitis is caused by bacteria, the infection may not require treatment, either. But if it is persistent or severe, then antibiotics — such as amoxicillin, doxycycline and others — may be used to treat the infection.
Allergies can produce many of the same cold-like symptoms as a sinus infection, including sinus pressure, a runny nose and congestion. But the condition itself, called allergic rhinitis, is different. It is caused by an allergic response to allergens, such as pollen, dust mites or pet dander. This reaction happens when your immune system releases chemicals, such as histamine, into your bloodstream. These immune system chemicals lead to your allergy symptoms.
One of the key ways to tell if you are experiencing allergic rhinitis is if you have itchy, watery eyes along with your other symptoms. Itchiness is rarely a symptom of a sinus infection. Another way to tell the difference is if you have very thick yellow or green nasal discharge. That is more likely a symptom of a sinus infection.
If you have seasonal allergies triggered by pollen or spores, then the timing of your symptoms may help you decide if they are likely caused by allergies. For example, tree pollen is most common in the spring. Grass pollen is common in late spring and early summer, while ragweed pollen is prevalent in the fall. Mold and fungi spores are usually more plentiful in warm-weather months. The seasons for these allergens may be different, though, depending on the region of the country where you live.
Over-the-counter medications, such as antihistamines, can be quite effective in relieving allergy symptoms. If you are regularly bothered by allergies, ask your doctor if a prescription nasal corticosteroid may be right for you. These nasal sprays help prevent and treat nasal inflammation and congestion, while antihistamines treat the itching and runny nose that allergies can cause.
Nasal corticosteroids can be particularly helpful if you have seasonal allergies and use them just as the allergy symptoms begin. That's because when the season first starts, you need a lot of the allergen to cause symptoms. But as symptoms progress, lower amounts of allergen produce more symptoms. By starting the medication early, you might be able to diminish this effect and reduce your symptoms throughout the entire allergy season.
If you suspect your nasal congestion and other symptoms are the result of sinus problems rather than allergies, you may just need to be patient, take care of yourself and use over-the-counter medications as needed until the infection clears. However, if symptoms last for more than two weeks, or if they are severe, make an appointment to see your doctor.
— Juan Guarderas, M.D., Otorhinolaryngology and Allergy, Mayo Clinic, Jacksonville, Fla.