A peanut allergy is a reaction that occurs when your body mistakenly identifies peanuts as harmful substances. When you eat peanuts or food containing peanuts, your immune system —the body's natural defense system that fights infections and diseases—overreacts and can cause a serious, even life-threatening response.
An allergic reaction occurs when your immune system overreacts and releases chemicals, including histamine, into your blood. These chemicals can affect different tissues in the body, such as the skin, eyes, nose, airways, intestinal tract, lungs, and blood vessels. It's not clear why peanuts trigger this response in some people.
Symptoms of peanut allergy can range from mild to severe. If you have a mild reaction, you may get a stomachache, a runny nose, itchy eyes, hives, or tingling in your lips or tongue. Your symptoms may start from within a few minutes to a few hours after eating peanuts or peanut products.
People who are allergic to peanuts may have a life-threatening reaction called anaphylaxis. Symptoms of anaphylaxis can include problems breathing and swallowing; vomiting and diarrhea; dizziness; dangerously low blood pressure; swelling of the lips, tongue, throat, and other parts of the body; and loss of consciousness. If not treated, death can result. Anaphylaxis usually occurs within minutes but can occur up to several hours after eating peanuts or peanut products.
To diagnose a peanut allergy, your doctor will start with a medical history and a physical exam. Your doctor will ask about any family food allergies, especially siblings with peanut allergies. He or she will ask detailed questions about your symptoms, how soon your symptoms began after you ate the food, and if any over-the-counter allergy medicines like an antihistamine were helpful. Your doctor will ask if other people also got sick, how the food was prepared, and what other foods were eaten.
It's important to find out whether you have a food allergy or food intolerance. Your doctor may ask you to keep a record of all the foods you eat and any reactions to the foods. Your doctor will also consider if your reaction could have been caused by things like allergies to medicines or insect stings, food poisoning, irritants in foods, and exposure to skin irritants.
Your doctor may ask you to try an elimination diet, an oral food allergy challenge, or both.
You may also have allergy tests, such as skin tests or blood tests, to determine what foods you are allergic to after you have been diagnosed with having a food allergy.
If you accidentally eat a peanut, follow your doctor's instructions. For a mild reaction, to reduce your symptoms you may only need to take an antihistamine, such as a nondrowsy one like loratadine (Claritin) or one that might make you sleepy like diphenhydramine (Benadryl). Mild symptoms include sneezing or an itchy or runny nose; an itchy mouth; a few hives or mild itching; and mild nausea or stomach discomfort.
If you have had a severe reaction previously, your doctor has probably prescribed a medicine called epinephrine. If you have symptoms in more than one body area, such as mild nausea and an itchy mouth, give yourself an epinephrine shot. Call 911 for further instructions.
For more information on how to give an epinephrine shot, see:
Even if you feel better after giving yourself the shot, symptoms of anaphylaxis can recur or suddenly appear hours later. You need to be observed in a hospital for several hours after your symptoms go away.
If you do not have epinephrine and are having a severe allergic reaction, call 911 immediately.
To prevent an allergic reaction to peanuts:
If you think you are having an allergic reaction:
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