Cough. Sneeze. Wheeze. You know the symptoms, but do you really know the cause? The similarities between symptoms of the flu/cold and nasal allergies (also called allergic rhinitis, indoor or outdoor allergies, seasonal allergies or hay fever) can cause confusion. Worse, it can cause you to make the wrong diagnosis and treat with the wrong medications. And, if allergies are left untreated, it can cause more serious conditions like sinusitis or ear infections. Learn about the difference below, and talk to your doctor about a complete medical exam to find out for sure:

Allergies Flu/Cold
Symptoms Allergies usually cause runny nose (clear discharge), stuffed nose, violent sneezing, wheezing, coughing, watery and itchy eyes. Flu/cold usually includes runny nose (yellow discharge), aches and pains, sore and scratchy throat along with sneezing and coughing.
Fever There is no fever with allergies. If you have a fever it is almost certainly a flu/cold rather than allergies.
When Anytime of the year: spring, summer, fall or winter. Usually appear in winter, but are also possible in the fall, spring or summer.
Warning Symptoms begin almost immediately after exposure to allergens. Usually takes a few days for flu/cold symptoms to appear.
Duration Symptoms last a long time, as long you are exposed to the allergen. If the allergen is present all year long, symptoms can be chronic. Flu/cold symptoms should clear up within a few days to a week. Rarely lasts more than 10 days.

Flu/Colds A flu/cold is commonly caused by a virus. You can get a flu/cold from another person that has that virus, even though you may be in good health. This happens when you breathe in germs or come in direct contact with the infected person. To prevent yourself from getting a flu/cold, get a flu shot every year, frequently wash your hands, use a disinfectant and be careful when sneezing and coughing around others. Let a flu/cold run its course. Get rest, drink lots of fluids and eat healthy foods. Over-the-counter medications, like a decongestant or a nasal sprays, can help relieve your symptoms, but they do not cure your cold – only time can do that. Allergies Nasal allergies occur during exposure to an allergen, and your nasal cavity becomes irritated and inflamed. Unlike the flu/cold, allergies are not contagious. If you have a high temperature or an achy body, it is most likely a flu/cold rather than allergies. Common indoor and outdoor allergens include tree, grass and weed pollen, dust mites, animal dander, mold and cockroaches. There is no cure for allergies, but there are prescription and over-the-counter medications that treat allergy symptoms. For some people, allergy shots (immunotherapy), can help to reduce your sensitivity to allergens over time. Talk to your doctor about the best treatment plan for you. SOURCE: This information should not substitute for seeking responsible, professional medical care. First created 1995; fully updated 1998; most recently updated 2005.
© Asthma and Allergy Foundation of America (AAFA) Editorial Board