Infection or allergies? You may be wondering about a respiratory tract infection such as a cold or even COVID-19 as the cause of your symptoms. Generally, people with allergies will have mucus from the nose or throat, which is clear. Also, allergies are much more likely to cause itchy or watery eyes and sniffles that last longer thana week. Furthermore, respiratory tract infections can cause fever and tend to intensify in symptoms the first week while allergy symptoms are constant.