Symptoms:

Symptoms usually begin immediately, within 2 hours after eating. Rarely, the symptoms may begin hours after eating the offending food.

If you develop symptoms shortly after eating a specific food, you may have a food allergy. Key symptoms include hives, hoarse voice, and wheezing.

See also:

• A video about what cause hives
• A video about what causes wheezing

Other symptoms that may occur include:

• Abdominal pain
• Diarrhea
• Difficulty swallowing
• Itching of the mouth, throat, eyes, skin, or any area
• Lightheadedness or fainting
• Nasal congestion
• Nausea
• Runny nose
• Patches of itchy, scaly skin (atopic dermatitis); skin may peel or blister
• Swelling (angioedema), especially of the eyelids, face, lips, and tongue
• Shortness of breath
• Stomach cramps
• Vomiting

Symptoms of mouth (oral) allergy syndrome:

• Itchy lips, tongue, and throat
• Swollen lips (sometimes)

Signs and tests:

In severe reactions, you may have low blood pressure and blocked airways.

Blood or skin tests are sometimes used to confirm that you have an allergy. However, there is no well-accepted criteria for diagnosing food allergies.

With elimination diets, you avoid the suspected food until your symptoms disappear. Then the foods are reintroduced to see if you develop an allergic reaction.

In provocation (challenge) testing, you eat a small amount of the suspected food allergen under medical supervision. This type of test may provoke severe allergic reactions. Challenge testing should only be done by a doctor.

Never try to deliberately cause a reaction or reintroduce a food on your own. These tests should only be performed under the guidance of a health care provider -- especially if your first reaction was severe.

See: Allergy testing