Allergies are caused by the body's overzealous reaction to normally harmless substances. Allergies can be triggered by pollen, animal dander, mold, dust, and insect droppings, or by certain foods or insect stings. Upper respiratory allergy symptoms include runny nose, itchy eyes, coughing, wheezing, and sneezing.
Man sits in bed at night blowing his nose.
Allergies That Might Seem Surprising
A senior woman sits in the doctor's office and touches her chin while talking to a female dermatologist.
How Are Hives Treated?
A man blows his nose
Why Nasal Congestion Happens—And How to Treat It