An allergic reaction to a substance causes an immediate reaction from the body’s immune system. Symptoms include runny nose and congestion, itchy or watery eyes, sneezing, cough, sinus pressure and pain, itchy nose and allergic swelling.

Differentiating hay fever from a cold can be tricky, given that the symptoms are so similar. Typically, hay fever causes a runny nose with a thin, watery discharge; fever is absent. With a cold, your runny nose will be accompanied by a thicker, yellow discharge, and you may experience body aches and fever. Your doctor can order tests to verify that hay fever is the cause of your symptoms.

Hay fever is often seasonal in nature, especially when triggered by pollen. Trees, grasses and weeds all release pollen as they bloom in the spring and summer. Other allergens, like dust mites and animal dander, produce symptoms year-round. The extent of your symptoms depends on which substance you are allergic to and how frequently it occurs.

If left untreated, hay may lead to sinus and ear infections, poor sleep and asthma. Avoiding the allergens that trigger your body’s immune system response is the best way to prevent hay fever. It can be tough to avoid all traces of these substances, of course, making medical treatment necessary for many people.

Drugs – including antihistamines, decongestants and nasal or oral corticosteroids – are often helpful. Over-the-counter medications work fine in many cases, but if you aren’t finding relief from those, your doctor may prescribe stronger medications. Allergy shots and drops (immunotherapy) offer long-term relief when other options fail; these work by allowing your body to build up a tolerance to the offending substance by introducing gradually increasing exposure over time.