Patient education: Peanut allergy (The Basics)

What is a peanut allergy? — A peanut allergy is when a person's immune (infection-fighting) system responds as if peanuts are harmful to the body. Most often, allergic reactions happen from eating peanut or food that contains peanut. Less often, allergic reactions happen when an allergic person breathes in tiny pieces or dust, like from a package of peanuts. Touching peanut can also cause a skin reaction.

What are the symptoms of an allergic reaction? — Common symptoms include:

●Hives, which are raised or puffy areas of skin that are itchy (picture 1)

●Puffiness of the face, eyelids, ears, mouth, hands, or feet

●Swelling of the tongue (picture 2)

●Trouble breathing, noisy breathing (wheezing), or coughing

●Nausea, vomiting, or diarrhea

●Feeling dizzy or passing out

●Death (although this is very rare)

The above symptoms usually show up quickly, minutes to hours after eating peanut. A severe allergic reaction is also called "anaphylaxis." When a person has anaphylaxis, they can get very sick, very quickly.

Although uncommon, a peanut allergy also sometimes triggers other symptoms. When this happens, it is usually hours to days after eating peanut. These symptoms include:

●Eczema – This is a skin condition that makes the skin itchy and flaky.

●Eosinophilic esophagitis – This is a condition that makes it hard to swallow food or causes heartburn.

Is there a test for a peanut allergy? — Yes. Your doctor or nurse will ask about the foods you eat and the symptoms you have. They will also do a test to check for a peanut allergy. Tests can include:

●A skin test – This involves pricking your skin with a device that contains a tiny amount of peanut. The test is positive if you get an itchy bump, like a mosquito bite, where your skin was pricked.

●Blood tests – These tests check the level of "IgE antibodies" in your blood. Antibodies are a type of protein. The body makes IgE antibodies when it is having an allergic reaction to something.

One blood test looks for IgE to whole peanut. Another test, called "component testing," looks for IgE to several different proteins found in peanuts. These test results can give your doctor more information about your allergy and how best to manage it.

Some people have a test called a "food challenge." This involves gradually eating a serving of peanuts and seeing whether it causes symptoms. For safety reasons, this test is done only in a doctor's office or hospital. Usually, a food challenge is only done if other tests are not clear, or if a doctor wants to check if a person's allergy has gone away.

Can peanut allergy be cured? — As of now, there is no definite cure for a peanut allergy. A treatment called "oral immunotherapy" might lower the risk of an allergic reaction if a person is accidentally exposed to peanut. Oral immunotherapy involves giving a child tiny amounts of peanut in a controlled way. The treatment is started in a clinic or hospital, where the child can be monitored and treated if they have a reaction. Then, they continue to take daily doses at home. The goal is to increase the dose of peanut very slowly over time, so the immune system doesn't react to it. Each dose increase is done in the clinic or hospital.

This type of treatment comes with risks and is not likely to make a person's allergy go away completely. But it might be an option in certain situations. If you are interested in learning more about oral immunotherapy, talk with your child's doctor or nurse.

How are allergic reactions treated? — Severe allergic reactions to peanuts are usually treated with medicine called epinephrine. Epinephrine comes in a device called an "auto-injector." This device gives you a shot of epinephrine (picture 3). When your doctor prescribes an auto-injector, they will show you how to use it and give you instructions for when to use it. Keep your auto-injector with you at all times. Most doctors recommend carrying 2 auto-injectors in case you need a second dose.

After you use an auto-injector, call for an ambulance (in the US and Canada, dial 9-1-1). Epinephrine doesn't last very long in the body, and symptoms can sometimes come back as it wears off. In the hospital, doctors can watch you and give you more medicine if needed.

If you think someone is having a severe allergic reaction and you do not have an epinephrine auto-injector, call for emergency medical help right away.

How can I prevent an allergic reaction? — The only way to prevent an allergic reaction is to completely avoid eating peanuts or foods with peanuts in them. To know whether a food contains peanuts, you will need to read its ingredient label. Some countries (including the United States) have laws that make companies clearly list whether a food has peanuts in it.

Some foods have warning labels for food allergies, such as "May contain peanuts." These foods might have been made on machines or in factories that also made other foods with peanuts. Doctors usually recommend that people with a peanut allergy avoid these foods.

Foods that are especially likely to contain peanuts include baked goods and Asian, African, and Mexican foods. If you eat at a restaurant, bakery, or ice cream parlor, be sure to tell your server about your peanut allergy.

What else should I know if I have a peanut allergy? — People with a peanut allergy:

●Can have an allergic reaction if they share saliva with (kiss) someone who ate peanuts and did not brush his or her teeth afterward

●Cannot have an allergic reaction by only smelling peanut butter

●Might have an allergic reaction by breathing in peanut dust or peanut protein, for example, when someone cooks with peanuts (if they are very allergic)

●Might get hives on their skin if they touch peanuts or peanut butter

●Sometimes have allergies to other foods, too, so might need to avoid eating certain other foods

What if my child has a peanut allergy? — If your child has a peanut allergy, let his or her caregivers, schools, and camps know. You should:

●Tell them which foods your child can and can't eat.

●Make a plan so they know how to treat an allergic reaction.

●Make sure they know where your child's epinephrine auto-injector is and how and when to use it.

●Make sure they know how to reach you or your child's doctor in case of an emergency.

Will my child outgrow his or her peanut allergy? — Most children do not outgrow their peanut allergy, but some do. Your child's doctor will monitor your child's peanut allergy over time to see whether they outgrow it.

Where can I get more information? — You can get more information about peanut allergies (and other food allergies) from an organization called Food Allergy Research & Education. Their website is www.foodallergy.org.

More on this topic

Patient education: Food allergy (The Basics)
Patient education: Anaphylaxis (The Basics)
Patient education: Angioedema (The Basics)
Patient education: Epinephrine autoinjectors (The Basics)
Patient education: Hives (The Basics)
Patient education: Eczema (atopic dermatitis) (The Basics)
Patient education: Eosinophilic esophagitis (The Basics)

Patient education: Food allergy symptoms and diagnosis (Beyond the Basics)
Patient education: Anaphylaxis symptoms and diagnosis (Beyond the Basics)
Patient education: Using an epinephrine autoinjector (Beyond the Basics)
Patient education: Eczema (atopic dermatitis) (Beyond the Basics)