Allergic Reactions vs. Viral Infection
While seasonal allergies and viral infections may have similar symptoms, it’s easy to differentiate the two. Here’s how:
Seasonal allergies are triggered by exposure to allergens. An allergic reaction is caused by our sensitized mast cells in the sinus, nose, eyes, mouth, and throat area. When these cells are exposed to an allergen, they release histamines, which are responsible for allergic inflammation.
Unlike allergies, a viral infection occurs as a cascade of events, mediated by immunologic messengers as a result of being infected. A good indicator that you have a viral infection is whether you’ve been exposed to someone who also has these same symptoms and whether you have a fever. Respiratory viruses—like COVID-19 and the flu—are easily spread between people who are in close contact.
It’s important to differentiate between allergic reactions and symptoms of a viral infection. It’s all in the pattern, explains Aaron Kobernick, MD, an allergist and assistant professor in the Department of Dermatology at University of Utah Health. Allergic reactions can include anything from itchiness in your eyes, nose, and mouth area to a runny nose or cough. However, these symptoms are not always indicative of a virus infection.
Common signs of a viral infection, like COVID-19, include fever, cough, and fatigue. While there are many other symptoms of an infection, a few symptoms of a viral infection aren’t associated with seasonal allergies.
“You just don’t get fevers from allergies like you do with the flu, COVID-19, or the common cold,” Kobernick says.
Additionally, allergies are generally worse outside and around pollen, whereas symptoms of a viral infection are generally worse in the evenings, regardless of whether you’re inside or outdoors.