Allergies - Symptoms

Symptoms depend on the specific kind of allergic reaction. Allergens in the air can cause an itchy, runny nose with post-nasal drip. Post-nasal drip occurs when fluid runs out of the back of the nose into the throat. When this happens, the throat can become scratchy and irritated. The thin membrane around the eye can also become irritated by allergens in the air. When this happens, the eye becomes red and itchy and begins to produce tears. Severe reaction to allergies may cause a disease called asthma. The symptoms of asthma include wheezing, coughing, and shortness of breath.

Food allergens can cause a variety of symptoms depending on a person's sensitivity to the allergen and the part of the body to which it goes. In the mouth and throat, an allergen can cause swelling and tingling in the lips, tongue, or throat. In the stomach, it can cause nausea, cramps, and diarrhea.

Contact dermatitis is marked by red, itchy skin that may develop skin blisters that ooze fluid.

Allergic reactions that spread throughout the body can occur with any kind of allergen. They tend to be more common, however, with allergens that enter the bloodstream through an insect bite or injection. Anaphylaxis is one of the most dangerous of these reactions.