Respiratory allergies and colds look and feel a lot alike. Both cause sneezing, a runny or stuffy nose, and tiredness. But unlike allergies, colds are caused by a virus, so you can spread them to other people. A cold probably won’t give you itchy eyes. But you may have aches, pains, or a fever, which don't happen with allergies. Colds last 3-10 days. Allergies, though, can last an entire season or longer.