Inhalant allergy or atopy is a kind of allergic reaction that results from the body's natural defense mechanism when exposed to allergens.  An allergic response occurs when your body reacts to an allergen, such as a virus or bacteria, causing symptoms like a runny nose, watery eyes, and asthma. For treatment, you can get antihistamines to relieve the symptoms and inhale steroids available over the counter or prescriptions by a physician.