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?
Your body’s immune system fights off infections and other dangers to keep you healthy.
When your immune system senses that a food or something in a food is a danger to your
health, you may have a food allergy reaction. Your immune system sends out IgE (immunoglobulin
E) antibodies. These react to the food or substance in the food. Your body releases
histamine and other substances. 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.
Most food allergies are caused by these foods:
Food protein-induced enterocolitis syndrome (FPIES) is also called the delayed food
allergy. FPIES often occurs in young babies. It causes vomiting and severe fluid loss
(dehydration). The most common cause of FPIES is having milk, soy, or grains.
What are the symptoms of a food allergy?
Allergic symptoms may begin within minutes to an hour after eating the food. Symptoms
may be a bit different for each person. Symptoms may include:
Severe nausea or vomiting
Stomach cramps or stomach pain
Red, itchy rash (hives)
Itching or swelling of the lips, tongue, or mouth
Throat itching or tightness
Feeling dizzy with a lowered blood pressure
Asthma symptoms such as coughing, runny or stuffy nose, wheezing, or trouble breathing
The symptoms of a food allergy may look like other health problems. Always see your
healthcare provider for a diagnosis.
Severe symptoms of a food allergy
Anaphylaxis is a severe allergic reaction. It is life-threatening. Symptoms can include:
Trouble breathing, shortness of breath, or wheezing
Feeling as if the throat is closing
Hoarseness or trouble talking
Swelling of the face, lips, tongue, and throat
Cool, moist, or pale blue skin
Feeling faint, dizzy, lightheaded, or confused (this could be from a drop in blood
Nausea, vomiting, or diarrhea
Fast and weak heartbeat
Loss of consciousness
Anaphylaxis is a medical emergency. Call 911 to get help right away. Severe allergic reactions are treated with epinephrine. You
should carry an emergency kit with self-injecting epinephrine. If you have emergency
injectable epinephrine, use it before you call 911.
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 health 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
Oral food challenge
Trial elimination diet
How is a food allergy treated?
At this time, no medicine is available to prevent food allergy. The goal of treatment
is to stay away from the food that causes the symptoms. This includes speaking up
when you are at a restaurant or at friends' homes. Let them know that you have a food
allergy. Don't be shy. And be clear that you could have a severe reaction if you eat
a food you are allergic to, even in small amounts.
If you have a food allergy, carry an epinephrine shot to treat emergency reactions.
Know how to give yourself this shot. You must be ready to treat any allergic reaction
caused by eating a food by mistake that you are sensitive to. You need an emergency
kit to stop severe reactions. Talk with your healthcare provider about what to do
with the kit.
Medicines are available to treat some symptoms of food allergy after the food has
been eaten. These medicines may ease nose and sinus symptoms, digestive symptoms,
or asthma symptoms.
Right now, no allergy shot treatment is approved to treat food allergies. But research
is ongoing. Strictly staying away from 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, eating out can be a challenge. But it is possible
to have a healthy and satisfying meal when dining out. 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 look over the menu items.
Let your server know from the start about your food allergy. Before you order, ask
how the dish is made and what is in it. If your server does not know this information
or seems unsure, ask to speak to the manager or the chef.
Don't go to buffet-style or family-style restaurants. There may be cross-contamination
of foods from using the same utensils for different dishes.
Don't eat fried foods. The same oil may be used to fry several different foods.
Carry your emergency injectable epinephrine whenever you go out to eat. Bring it to
restaurants and to other people's homes.
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 more information. This includes
a reminder to make sure all utensils and equipment used to make your meal are thoroughly
cleaned before use. You can easily print these cards yourself using a computer and
Clearer food labels with FALCPA
The Food Allergen Labeling Consumer Protection Act (FALCPA) was passed into law in
2004. It helps ensure clearer labeling of food by manufacturers. Here is more information
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
think you have a food allergy, see a healthcare provider for a diagnosis.
Carry an epinephrine shot to treat emergency reactions. Know how to give yourself
The goal of treatment is to stay away from 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.