|Step 1: What is an allergy?|
When most people think of an allergy, they think of the sneezing, congestion, and itchy eyes caused by pollen. In fact, allergies can be caused by just about any substance that you inhale or swallow, or that touches your skin. You can also be allergic to shots.
Your body's immune system is designed to attack harmful substances like bacteria and viruses. But with allergies, your body launches an assault far beyond what is called for on substances such as pollen, mold, dust mites, pet saliva and dander, and even medications and insect sting venom. Immunity is helpful protection against a substance. An allergy, meanwhile, is harmful hypersensitivity to that substance.
Allergies are extremely common, and they are on the rise. Already, about 50 million Americans suffer from allergies, leading to a lot of missed work and school days each year. Annual medical costs already exceed $4.5 billion.
Not only do allergies cause a range of annoying symptoms, such as sneezing and itchy eyes, but they can aggravate or trigger other conditions such as asthma, sinusitis, and ear infections. For example, when allergies cause inflammation in your nasal passages, the opening to your sinuses can become blocked, leading to sinus inflammation, sinus infections, and sinus pain. Similarly, allergies can cause the ears not to drain properly, which can lead to ear infections.
But allergies don't stop there. The body's immune system is active from your head to your toes: allergies can cause different skin-related symptoms (such as hives and eczema); some types of allergies can lead to gastrointestinal problems; and assorted allergy-related symptoms can affect other normal body functions (such as headaches, loss of smell, and sleep disturbances).
One of the most deadly kinds of allergic reaction is called "anaphylaxis," which is when the entire body has a swift, severe reaction to something such as foods (examples include peanuts, nuts, shellfish, or food additives), latex, medications (penicillin), or insect stings. The body literally goes into shock, leading to a sharp drop in blood pressure, respiratory arrest, and possible heart failure.
To continue to the next step of the allergy guide, click "next" below.
Wallace DV, Dykewicz MS, Bernstein DI, Blessing-Moore J, Cox L, Khan DA, et al. The diagnosis and management of rhinitis: an updated practice parameter. J Allergy Clin Immunol. 2008 Aug:122(2).
What is an Allergic Reaction? American Academy of Allergy, Asthma, and Immunology, Public Education Committee;2006.
Reviewed By: Frederic F. Little, M.D., Department of Allergy and Pulmonary/Critical Care Medicine, Boston University School of Medicine, Boston, MA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.