Telling the differences between allergies and a cold is often a matter of understanding the symptoms of each. From a purely medical standpoint, allergies are a histamine response to things you are allergic to, like pollens, mold, or dust mites. Colds, on the other hand, are the body’s response to dealing with a virus, typically a set of hundreds of rhinoviruses. There may be similarities between the two, but the differences between allergies and a cold can help you understand how to best address these separate conditions.

One of the early differences between allergies and a cold is onset of symptoms. Allergies generally occur quickly, with all symptoms, like runny nose, itchy eyes, and scratchy throat happening within a few hours of exposure to allergens. Cold symptoms tend to develop over a few days. You might one day have a slightly congested nose and a slightly scratchy throat, but it may take several days before your symptoms progress to a full-blown cold.

Nasal discharge can also signify one of the differences between allergies and a cold. Allergic nasal response tends to show discharge that is clear or white, and fairly thin. In the early days of a cold, nasal discharge is thicker, sometimes so thick it is difficult to clear the nose by blowing it. You should note with either allergies or colds continued nasal discharge that becomes thick brown, dark yellow or green might indicate a sinus infection.

How long you continue to have symptoms also can help you determine the differences between allergies and a cold. Generally a cold lasts for seven to fourteen days. Allergies, especially seasonal ones, can last for three weeks to several months. Colds can occur at any time of year, but allergies to pollen are likely to occur most often in spring and fall.

Both allergies and colds can cause feelings of fatigue, headaches, sneezing, coughing and asthma. Yet one of the differences between allergies and a cold is that colds from certain viruses may cause slight fevers. Allergies, though they are often called hayfever rarely cause fevers unless you have a sinus infection.

You might also notice that you can determine the differences between allergies and a cold by the medications you take. If you take a decongestant, this will be hard to determine. But if you take an antihistamine, your allergy symptoms are likely to resolve quickly, and may not return until you are re-exposed to allergens. An antihistamine may provide minor relief to cold symptoms but it will not eliminate them.

Though similarities exist in these two annoying conditions, recognizing the differences between allergies and a cold can help in preventing allergies. If you know you are prone to seasonal allergies, many antihistamines can help you almost completely eliminate allergy symptoms. It’s much harder to prevent a cold, though good handwashing practices certainly help.