Food allergy is an immune system reaction that occurs after eating certain foods. Even a small amount of the allergy-causing food can cause symptoms such as digestive problems, hives or swollen airways. In some cases, a food allergy can be severe causing serious symptoms or a life-threatening reaction called anaphylaxis.
There is no cure for food allergy; however, some children may outgrow their food allergy over time.
A food allergy is often confused for a common reaction known as food intolerance, which is a less serious condition that does not involve the immune system.
Food allergy symptoms range from mild to severe and even life threatening.
Common food allergy symptoms include:
- Tingling or itching in the mouth
- Hives, itching or eczema
- Swelling of the lips, face, tongue and throat or other body parts
- Abdominal pain, diarrhea, nausea or vomiting
- Wheezing, nasal congestion or difficulty breathing
- Dizziness, lightheadedness or fainting
Symptoms of anaphylaxis include:
- Constriction and tightening of airways
- Swollen throat or the sensation of a lump in the throat that causes difficulty breathing
- Shock with severe drop in blood pressure
- Rapid pulse
- Dizziness, lightheadedness or loss of consciousness
Anaphylaxis requires emergency medical treatment, otherwise it may lead to a coma or even death.
Exercise-induced food allergy
Some people have allergic reactions to food that are triggered by exercise. Symptoms may include itchiness, lightheadedness, hives or anaphylaxis.
Pollen-food allergy syndrome
Some people who have hay fever can have an allergic reaction to foods such as fresh fruits and vegetables as well as certain nuts and spices. The symptoms may include tingling or itching in the mouth. In some people, pollen-food allergy syndrome can cause swelling of the throat or even anaphylaxis. This type of reaction may be the result of cross-reactivity because proteins in fruits and vegetables are similar to the allergy-causing proteins found in certain pollens.
Pollen-food allergy syndrome may be avoided by cooking the food.
Most food allergies are triggered by certain proteins found in:
- Shellfish (shrimp, lobster and crab)
- Tree nuts (walnuts and pecans)
Food allergies in children are commonly triggered by proteins in:
- Tree nuts
Food intolerance and other reactions
Food intolerance can cause similar symptoms as a food allergy. However, in food intolerance, eating small amounts of problem foods may cause no or little reaction while a food allergy causes an allergic reaction after ingesting even a tiny amount of the certain food.
Common conditions that cause similar symptoms of food allergy:
- Absence of an enzyme needed to fully digest a food: For instance insufficient lactase enzymes cause lactose intolerance.
- Food poisoning: Bacteria in certain foods can trigger harmful reactions similar to an allergic reaction.
- Sensitivity to food additives: Certain food additives may trigger digestive problems and other symptoms.
- Histamine toxicity: Histamine toxicity can occur if certain fish are not refrigerated properly.
- Celiac disease: This is a chronic digestive condition triggered by eating gluten that may cause damage to the surface of the small intestine.
Factors that increase the risk of food allergy include:
- Family history of asthma, eczema, hives or allergies
- A past food allergy
- Other allergies
- Age (food allergies are more common in children who tend to outgrow certain food allergies)
Factors that increase the risk of anaphylaxis include:
- A history of asthma
- Being a teenager or younger
- Later rather than immediate epinephrine treatment for allergy
- Absence of hives or other skin symptoms
Possible complications of food allergy include:
- Atopic dermatitis (eczema)
- Check the contents of food and drinks
- Wear a medical alert bracelet or necklace to let others know in case of emergency
- Carry an emergency epinephrine autoinjector
- Be clear about orders in restaurants