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 have a food allergy reaction. Your immune system sends out immunoglobulin
E or IgE antibodies. These react to the food or substance in the food. Your body releases
histamines. 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:
- Tree nuts
What are the symptoms of a food allergy?
Allergic symptoms may begin within minutes to an hour after eating the food. Symptoms
can occur a bit differently in each person. Symptoms may include:
- Severe nausea or vomiting
- Stomach cramps or stomach pain
- Red, itchy rash (hives)
- Swelling of the face
- Itching or swelling of the lips, tongue, or mouth
- Itching or tightness in the throat
- 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 difficulty talking
- Swelling of the face, lips, tongue, and throat
- Cool, moist, or pale blue skin
- Feeling faint, lightheaded, or confused
- Nausea, vomiting, or diarrhea
- Fast and weak heartbeat
- Feeling dizzy, with a sudden drop in blood pressure
- 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.
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, no medicine is available to prevent food allergy. The goal of treatment
is to stay away from the food that causes the symptoms.
If you have a food allergy, you should carry with you and know how to give yourself
an epinephrine shot to treat emergency reactions. You must be ready to treat any allergic
reaction caused by accidentally eating a food 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, 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.