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Learning About Food Allergies

What is a food allergy?

When you have a food allergy and you eat that food, your body reacts as if the food is trying to harm you. So it fights back by setting off an allergic reaction. A mild reaction is no fun, but it isn't dangerous. A serious reaction can be deadly.

Allergies tend to run in families. You are more likely to have a food allergy if other people in your family have allergies like hay fever or asthma. And food allergies are more common in children than in adults. But if you develop a food allergy as an adult, you will most likely have it for life. Adults most often have allergies to peanuts, tree nuts, fish, or shellfish.

The best way to prevent a food allergy is to avoid the foods that cause it. And make sure that you know what to do if you do eat something you are allergic to.

What are the symptoms?

Food allergies can cause many different symptoms. They can range from mild to serious. A mild reaction may include tingly lips, a stuffy nose, dizziness, and a few raised, red, itchy patches of skin (called hives).

The most severe reaction is called anaphylaxis (say "ANN-uh-fuh-LAK-suss"). It affects your whole body. Anaphylaxis can start within a few minutes to a few hours after you eat the food. The symptoms can go away and come back hours later. A severe reaction may cause hives all over, swelling in the throat, trouble breathing, nausea or vomiting, or fainting.

How is a food allergy diagnosed?

Your doctor will ask questions about your past health and family food allergies. And he or she will do a physical exam. Your doctor will also ask what symptoms you have when you eat certain foods.

Because food allergies can be confused with other problems, your doctor may do some tests. You may have either skin testing or a blood test. These tests help to see what you are allergic to. An oral food challenge is another way to diagnose a food allergy. You will eat a variety of foods that may or may not cause an allergic reaction. Your doctor watches to see if and when a reaction occurs.

How can you prevent future reactions?

If you have a food allergy, you can take steps to avoid having reactions to that food. Most important, avoid eating the foods you're allergic to. Learn to read food labels and spot other names for problem foods. When you eat out or at other people's houses, ask about the foods you are served. And you can bring safe substitutes from home.

It's smart to teach your family members, co-workers, and friends what to do if you eat a food that you're allergic to.

Also, you can wear medical alert jewellery that lists your allergies.

How can you care for yourself at home?

During a mild reaction

  • Take a non-drowsy antihistamine, such as loratadine (Claritin), as your doctor recommends. Be safe with medicines. Read and follow all instructions on the label.

During a severe reaction

  • Give yourself an epinephrine shot. Keep it with you at all times. Make sure it has not expired.
  • Call for emergency help. A severe allergic reaction can be life-threatening and is a medical emergency.

To prevent future reactions

  • Avoid the foods that cause problems. And try not to use utensils or cookware that may have been in contact with food that you are allergic to.
  • Teach your family members, co-workers, and friends what to do if you have a severe reaction to a food that you are allergic to.
  • Wear medical alert jewellery that lists your allergies.

When should you call for help?

Give an epinephrine shot if:

  • You think you are having a severe allergic reaction.

After you give an epinephrine shot, call 911, even if you feel better.

Call 911 anytime you think you may need emergency care. For example, call if:

  • You have symptoms of a severe allergic reaction. These may include:
    • Sudden raised, red areas (hives) all over your body.
    • Swelling of the throat, mouth, lips, or tongue.
    • Trouble breathing.
    • Passing out (losing consciousness). Or you may feel very light-headed or suddenly feel weak, confused, or restless.
    • Severe belly pain, nausea, vomiting, or diarrhea.
  • You have been given an epinephrine shot, even if you feel better.

Call your doctor or nurse advice line now or seek immediate medical care if:

  • You have symptoms of an allergic reaction, such as:
    • A rash or hives (raised, red areas on the skin).
    • Itching.
    • Swelling.
    • Mild belly pain or nausea.

Watch closely for changes in your health, and be sure to contact your doctor or nurse advice line if:

  • You do not get better as expected.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse advice line (811 in most provinces and territories) if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Where can you learn more?

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