Anaphylaxis (an-a-fi-LAK-sis) is a serious allergic response that often involves swelling, urticaria*, lowered blood pressure and in severe cases, shock. If anaphylactic shock isn’t treated immediately, it can be fatal. A major difference between anaphylaxis and other allergic reactions is that anaphylaxis typically involves more than one system of the body. Symptoms usually start within 5 to 30 minutes of coming into contact with an allergen to which an individual is allergic. In some cases, however, it may take more than an hour to notice anaphylactic symptoms. Warning signs may include:

* Red rash (usually itchy and may have welts/hives)

* Swollen throat or swollen areas of the body

* Wheezing

* Passing out

* Chest tightness

* Trouble breathing

* Hoarse voice

* Trouble swallowing

* Vomiting

* Diarrhea

* Stomach cramping

* Pale or red color to the face and body


Anaphylaxis may occur in people with allergies to foods, insect stings, medications or latex. If you are at risk for anaphylaxis, be prepared with an anaphylaxis action plan and by carrying auto-injectable epinephrine*.



Antihistamines are the most widely used medications to relieve or prevent symptoms of allergic rhinitis (hay fever)*. Some antihistamines may also be used to treat chronic urticaria (hives)*. These medications reduce symptoms by preventing the effects of histamine—a chemical substance produced by the body during an allergic reaction. Antihistamines are available as a liquid, tablet or nasal spray. Different antihistamines are available either by prescription or over-the-counter (OTC). Newer antihistamines prescribed by your allergist / immunologist are less likely to have side effects such as drowsiness, dry mouth, constipation or difficulty urinating.