Tests and diagnosis

By Mayo Clinic Staff

The following may help determine if you have a peanut allergy or if your symptoms are likely due to something else, such as food intolerance, a bout of food poisoning or some other condition.

  • Description of your symptoms. Be prepared to tell your doctor about your symptoms — such as exactly what happened after you ate peanuts, how long it took for a reaction to occur, and what amount of peanuts or food containing peanuts caused your reaction.
  • Physical examination. A careful exam can identify or exclude other medical problems.
  • Food diary. Your doctor may ask you to keep a food diary of your eating habits, symptoms and medications to pinpoint the problem.
  • Elimination diet. If it isn't clear that peanuts are the culprit, or if your doctor suspects you may have a reaction to more than one type of food, an elimination diet may be needed. You may be asked to eliminate peanuts or other suspect foods for a week or two, and then add the food items back into your diet one at a time. This process can help link symptoms to specific foods. If you've had a severe reaction to foods, this method can't safely be used.
  • Skin test. A skin prick test can determine your reaction to particular foods. In this test, small amounts of suspected foods are placed on the skin of your forearm or back. Your skin is then pricked with a needle, to allow a tiny amount of the substance beneath your skin surface. If you're allergic to a particular substance being tested, you develop a raised bump or reaction.
  • Blood test. A blood test can measure your immune system's response to particular foods by checking the amount of allergy-type antibodies in your bloodstream, known as immunoglobulin E (IgE) antibodies. For this test, a blood sample taken in your doctor's office is sent to a medical laboratory, where different foods can be tested. However, these blood tests aren't always accurate.

Is it peanut allergy? Or is it peanut intolerance?

Not all reactions to peanuts are caused by an allergic reaction. It can be difficult to know whether you are allergic or intolerant to peanuts.

  • If you have peanut intolerance, you might be able to eat peanuts with only mild symptoms, such as indigestion or heartburn, or no reaction at all. A peanut intolerance doesn't involve your immune system.
  • If you have a true peanut allergy, eating even a small amount of peanuts may trigger a serious allergic reaction. Tests can help determine whether you have true peanut allergy.
Jun. 27, 2012