A viral allergen is a microorganism that causes allergic reactions in some people. It can be found in air, water, soil and on surfaces contaminated with organic matter such as feces, animal excrement, cleaning products and food. Viral allergens include influenza viruses, adenoviruses, rhinoviruses, coronaviruses and others.
Viruses belong to the kingdom of "cells". They are microscopic organisms that are made up of genetic material called DNA or RNA (different types of viruses may have one or the other of these substances) and a shell of protein. Most viruses are parasites and can infect other living things such as plants, animals and people.
One of the most common viral allergens is the cold or flu. This is a cold caused by the influenza virus. Symptoms of a cold may include fever and chills, headaches, weakness, sore throat and runny nose. People who are allergic to viruses may experience itching, sneezing, and breathing problems during or after contact with an infected person or place.