If you are allergic to a particular food, you may experience some or all of the following symptoms:
- Itching in your mouth and/or swelling of the lips
- Gastrointestinal (GI) symptoms, such as vomiting, diarrhea, or abdominal cramps and pain
- Hives or some other form of rash and reddening of the skin
- Tightening of the throat and trouble breathing
- Drop in blood pressure
First Allergic Reaction
Usually, the first reaction to a food allergen occurs when you eat that particular food. Sometimes, exposure can occur without your knowledge, such as when a food allergen is a small part of a larger meal or a mixture of different foods. It is the first exposures that prime the immune system to the food.
In the case of peanut allergy, you may not have to eat peanuts or peanut-containing foods to have an allergic reaction. A person who experiences an allergic reaction may have had contact with peanuts in any of the following ways:
- Touching peanuts
- Using a peanut-containing skin care product
- Breathing in peanut dust, such as when in close proximity to people eating peanuts
Cross-reactive Food Allergies
If you have a life-threatening reaction to a certain food, your healthcare professional can show you how to avoid similar foods that may also trigger the reaction. For example, if you have a history of allergy to shrimp, testing may show you are also allergic to other shellfish, such as crab, lobster, and crayfish. This is called cross-reactivity.
If you have had an adverse reaction to a food, see a doctor for evaluation. Although you may think you have had an allergic response, only your doctor can determine if that has been the case.
The guidelines recommend that your doctor first takes your detailed medical history and then performs a physical examination. If a food allergy seems likely, there are tests—such as the skin prick test or a blood test to detect allergen-specific antibodies—that will help identify the possible allergenic foods. However, these approaches alone cannot conclusively diagnose a food allergy.
The only definitive test is an oral food challenge. Because this test can place you at risk for a severe allergic reaction, it must always be performed by a healthcare professional who has the appropriate training and experience with treating the symptoms of a severe allergic reaction.