What is a food allergy?
A food allergy is when your immune system has a bad reaction to a certain food. This
is different from a food intolerance, which does not affect the immune system. This
is true even though some of the same signs may be present.
What causes a food allergy?
Before having a food allergy reaction, a sensitive person must have eaten the food
at least once before. It is the second time the person eats the food that the allergic
symptoms happen. At that time, when Immunoglobulin E or IgE antibodies react with
the food, histamines are released. This can cause hives, asthma, itching in the mouth,
trouble breathing, stomach pains, vomiting, or diarrhea. It does not take much of
the food to cause a severe reaction in highly allergic people.
Almost all food allergies are caused by 8 foods:
- Tree nuts
Eggs, milk, and peanuts are the most common causes of food allergies in children.
Peanuts, tree nuts, fish, and shellfish usually cause the most severe reactions. Although
many children “outgrow” their allergies, allergy to peanuts, tree nuts, fish, and
shellfish may be life long.
What are the symptoms of a food allergy?
Allergic symptoms may begin within minutes to an hour after eating the food. Symptoms
- Itching or swelling of the lips, tongue, or mouth
- Itching or tightness in the throat
- Trouble breathing
- Lowered blood pressure
How is a food allergy diagnosed?
If you think you have a food allergy, see your healthcare provider for a diagnosis.
He or she will take your medical history and do a physical exam. The healthcare provider
will do skin or blood tests or both to find out the exact diagnosis. These tests may
- Skin prick test
- Blood test
- Oral food challenge
- Trial elimination diet
How is a food allergy treated?
At this time, there is no medicine available to prevent food allergy. The goal of
treatment is to avoid the food that causes the symptoms.
If you have a food allergy, you should carry and know how to give yourself an epinephrine
shot to treat emergency reactions. People with food allergy must be prepared to treat
any accidental ingestion of the foods that cause the allergic reaction.
There are medicines available to treat some symptoms of food allergy after the food
has been eaten. These medicines may relieve rhinitis symptoms, gastrointestinal symptoms,
or asthma symptoms.
Right now, there is no allergy shot treatment approved for the treatment of food allergies.
However, research is ongoing. Strictly avoiding the allergy-causing food is the only
way to prevent a reaction.
Living with a food allergy
If you have one or more food allergies, dining out can be a challenge. However, it
is possible to have a healthy and satisfying dining-out experience. It just means
that you may have to plan ahead when you eat out.
Here are some tips for dealing with food allergies when you are eating away from home.
- Know what ingredients are in the foods at the restaurant where you plan to eat. When
possible, get a menu from the restaurant ahead of time and review the menu items.
- Let your server know from the beginning about your food allergy. Ask how the dish
is prepared and what is in it before you order. If your server does not know this
information or seems unsure of it, ask to speak to the manager or the chef.
- Avoid buffet-style or family-style service. There may be cross-contamination of foods
from using the same utensils for different dishes.
- Avoid fried foods, as the same oil may be used to fry several different foods.
Another tip for dining out is to carry a food allergy card. You can give it your server
or the manager before you order food. A food allergy card contains information about
the specific items you are allergic to. It also has additional information such as
a reminder to make sure all utensils and equipment used to prepare your meal are thoroughly
cleaned before use. You can easily print these cards yourself using a computer and
Key points about a food allergy
- A food allergy is when your immune system has a bad reaction to a certain food. Before
having a food allergy reaction, a sensitive person must be exposed to the food at
least once before.
- Most allergies are caused by milk, eggs, wheat, soy, tree nuts, peanuts, fish, and
- Allergic symptoms may begin within minutes to an hour after eating the food. If you
suspect you have a food allergy, you should see a healthcare provider for a diagnosis.
- At this time, no medicine is available to prevent food allergy.
- The goal of treatment is to avoid the food that causes the symptoms.
Tips to help you get the most from a visit to your healthcare provider:
- Know the reason for your visit and what you want to happen.
- Before your visit, write down questions you want answered.
- Bring someone with you to help you ask questions and remember what your provider tells
- At the visit, write down the name of a new diagnosis, and any new medicines, treatments,
or tests. Also write down any new instructions your provider gives you.
- Know why a new medicine or treatment is prescribed, and how it will help you. Also
know what the side effects are.
- Ask if your condition can be treated in other ways.
- Know why a test or procedure is recommended and what the results could mean.
- Know what to expect if you do not take the medicine or have the test or procedure.
- If you have a follow-up appointment, write down the date, time, and purpose for that
- Know how you can contact your provider if you have questions.