Winter weather brings winter health problems, but wait before reaching for the cold medicine. Cold symptoms often mimic allergy symptoms, and it’s important to tell them apart so you don’t treat the wrong thing. The symptoms of the two can be very similar—runny nose, coughing, nose and chest congestion—but the causes are quite different.
Colds are viral infections. Specifically, the cold symptoms you experience are the body’s reaction to a viral infection. The congestion and blockages result from the immune system attacking any of hundreds of what are called rhinoviruses. Allergies, by contrast, are caused by a similar immune response but to normally harmless substances such as dust or pollen. While pollen is more common in spring and fall, dust is year-round, particularly for people with kids or pets.
That means, first of all, that colds are contagious and allergies are not. You can spread a cold, if you’re not careful—though you can avoid it by washing your hands regularly. Allergies are not contagious. While a tendency to develop allergies may be hereditary, the allergies themselves do not spread from person to person the way a cold or other viral illness does.
Another important difference is duration. A cold usually lasts less than two weeks—one that lingers longer than that is probably allergies. Colds come on gradually, a few days after infection, while allergy symptoms develop immediately upon exposure, meaning that allergies usually strike around the same time every year, with less variation than a cold. Anyone who talks about their "annual cold" probably has allergies, if not instead, possibly as well.
So how can you tell the which one is which? Aside from differences in onset and duration, the symptoms, though superficially similar, actually are different if you pay attention. Coughing, a sore throat, and yellow mucous generally mean a cold, and the achy feeling definitely does—that’s not an allergic reaction. On the other hand, itchiness in the eyes almost certainly is, and allergy mucous is clear. Lastly, while fever is rarely a cold symptom, it is never an allergic one.