Food allergy is an immune system reaction that occurs soon after eating a certain food. Even a tiny amount of the allergy-causing food can trigger signs and symptoms such as digestive problems, hives, or swollen airways. In some people, a food allergy can cause severe symptoms or even a life-threatening reaction is known as anaphylaxis.
Food allergy affects an estimated 6 to 8 percent of children under age 3 and up to 3 percent of adults. While there’s no cure, some children outgrow their food allergies as they get older.
It’s easy to confuse a food allergy with a much more common reaction known as food intolerance. While bothersome, food intolerance is a less serious condition that does not involve the immune system.
When you have a food allergy, your immune system mistakenly identifies a specific food or a substance in food as something harmful. In response, your immune system triggers cells to release an antibody known as immunoglobulin E (IgE) to neutralize the allergy-causing food or food substance (the allergen).
The next time you eat even the smallest amount of that food, IgE antibodies sense it and signal your immune system to release a chemical called histamine, as well as other chemicals, into your bloodstream. These chemicals are food allergy causing symptoms.
In adults, the majority of food allergies are triggered by certain proteins in:
- Shellfish, such as shrimp, lobster, and crab
- Tree nuts, such as walnuts and pecans
In children, food allergies are commonly triggered by proteins in:
- Tree nuts
For some people, an allergic reaction to a particular food may be uncomfortable but not severe. For other people, an allergic food reaction can be frightening and even life-threatening. Food allergy symptoms usually develop within a few minutes to two hours after eating the offending food.
The most 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 parts of the body
- Wheezing, nasal congestion, or trouble breathing
- Abdominal pain, diarrhea, nausea, or vomiting
- Dizziness or fainting
In some people, a food allergy can trigger a severe allergic reaction called anaphylaxis. This can cause life-threatening signs of food allergy, including:
- Constriction and tightening of the airways
- A swollen throat or the sensation of a lump in your throat that makes it difficult to breathe
- Shock with a severe drop in blood pressure
- Rapid pulse
- Dizziness, lightheadedness, or loss of consciousness
Emergency food allergies treatment is critical for anaphylaxis. Untreated, anaphylaxis can cause a coma or even death.
There’s no perfect test used to confirm or rule out a food allergy. Your doctor will consider a number of factors before making a food allergies diagnosis. These factors include.
- Family history of allergies: Also share information about members of your family who have allergies of any kind.
- A physical examination: A careful exam can often identify or exclude other medical problems.
- A skin test: A skin prick test can determine your reaction to a particular food. In this test, a small amount of the suspected food is placed on the skin of your forearm or back. A doctor or another health professional then pricks your skin 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. Keep in mind, a positive reaction to this test alone isn’t enough to confirm a food allergy.
- A blood test: A blood test can measure your immune system’s response to particular foods by measuring the allergy-related antibody known as immunoglobulin E (IgE).
For this test, a blood sample taken in your doctor’s office is sent to a medical laboratory, where different foods can be tested.
- Elimination diet: You may be asked to eliminate 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. However, elimination diets aren’t foolproof.
An elimination diet can’t tell you whether your reaction to a food is a true allergy instead of a food sensitivity. Also, if you’ve had a severe reaction to a food in the past, an elimination diet may not be safe.
- Oral food challenge. During this test, done in the doctor’s office, you’ll be given small but increasing amounts of the food suspected of causing your symptoms. If you don’t have a reaction during this test, you may be able to include this food in your diet again.
The only way to avoid an allergic reaction is to avoid the foods that cause signs and symptoms. However, despite your best efforts, you may come into contact with a food that causes a reaction.
For a minor allergic reaction: Over-the-counter or prescribed antihistamines may help reduce symptoms. These drugs can be taken after exposure to an allergy-causing food to help relieve itching or hives food allergy. However, antihistamines can’t treat a severe allergic reaction.
For a severe allergic reaction: You may need an emergency injection of epinephrine and a trip to the emergency room. Many people with allergies carry an epinephrine auto injector. This device is a combined syringe and concealed needle that injects a single dose of medication when pressed against your thigh.
When To See A Doctor
See a primary care physician or allergist if you have food allergy symptoms shortly after eating. If possible, see your doctor when the allergic reaction is occurring. This will help your doctor make a diagnosis.
This information is intended for educational purposes only and should not be considered a substitute for professional medical advice. If you have concerns about food allergies or any other medical condition, please see a doctor for an accurate diagnosis and personalized treatment suggestions.