Food allergy

Diagnosis

Your healthcare professional does a complete physical exam and asks a number of questions about:

• Symptoms.
• Diet.
• Foods that seem related to symptoms.
• The timing from eating a food to having symptoms.
• Family history of allergies.

Allergy tests

Allergy tests can help your healthcare team find foods that may cause an allergic reaction. A negative result means that you may not be allergic to a particular food. A positive result means that you may be allergic to that food.

The results show whether your body has antibodies to a food allergen. They don't necessarily show that you will actually have an allergic reaction to the food. The test results can help your healthcare team figure out how likely you are to be allergic to a food and how to move forward with more tests or treatments.

Allergy tests include:

• Skin prick test. A small amount of the suspected food is placed on the skin of your forearm or back. A healthcare professional then pricks your skin to allow a tiny amount of the substance beneath your skin surface. If your body has antibodies to that food allergen, a raised bump appears.
• Blood tests. Laboratory tests of a blood sample can identify the presence of antibodies to a particular food allergen.

Oral food challenge

This test is done with a healthcare team that has experience with interpreting the reactions to the test and treating the symptoms. There is a risk of anaphylaxis, which must be treated immediately.

For two weeks before the test, the suspect food isn't eaten. No food is eaten for two hours before the test. You may be asked not to take certain medicines.

During this test, you're given small but increasing amounts of the food suspected of causing your symptoms. An allergic reaction confirms that you are allergic to that food. If you don't have a reaction, you may be able to include this food in your diet.

Treatment

The primary approach to food allergy is to strictly avoid the food that causes the allergic reaction. But you may need treatment if you come in contact with the food allergen or accidentally eat it

Medicines

Medicines may lessen symptoms or prevent symptoms when you are accidentally exposed to a food allergen.

• Antihistamines. For a minor allergic reaction, prescribed antihistamines or those you can buy without a prescription may help reduce symptoms. These medicines may help relieve itching or rash. They cannot treat more severe symptoms, such as breathing difficulties.
• Peanut allergen powder. Peanut allergen powder-dnfp (Palforzia) is a type of immunotherapy. This treatment helps prevent allergic reactions after accidental exposure to peanuts. It doesn't allow you to eat peanut products. It can be prescribed to children with peanut allergy who are ages 4 to 17. It can be taken as a maintenance medicine in adulthood.
• Omalizumab. Omalizumab (Omlyclo, Xolair) is a type of medicine called a monoclonal antibody. Regular injections of omalizumab may reduce food allergy reactions if small amounts of a food allergen are eaten by mistake. This medicine is approved for children age 1 and older and for adults.

Anaphylaxis treatment

Many people with food allergies are prescribed an epinephrine autoinjector (Adrenaclick, EpiPen, others). This device is a combined syringe and concealed needle that injects a single dose of medicine when pressed against your thigh. Review how and when to use an epinephrine autoinjector with your healthcare professional.

Epinephrine also may be taken as a nasal spray. The brand name for the spray version is Neffy.

If you've been prescribed epinephrine:

• Be sure you know how to use epinephrine. Also, make sure the people closest to you know how to give the medicine. If they're with you in an anaphylactic emergency, they may need to give you a dose.
• Carry epinephrine with you at all times. It may be hard to predict when an accidental exposure may trigger an anaphylactic reaction.
• Always be sure to replace epinephrine before its expiration date, or it may not work properly.
• Work with your child's school. It's important to work with nurses, teachers and other school staff so they understand your child's need for epinephrine. Create an anaphylaxis action plan.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.

Lifestyle and home remedies

One of the keys to preventing an allergic reaction is to completely avoid the food that causes your symptoms.

• Read food labels to make sure they don't have an ingredient you're allergic to. Food labels must clearly list whether the food products have any common food allergens. Also, check the label to see if the food was made in a setting where the food allergen also is prepared.
• Plan meals and snacks before leaving home. If necessary, take a cooler packed with allergen-free foods when you travel or go to an event. If you or your child can't have the cake or other dessert at a party, bring an approved special treat so no one feels left out of the celebration.
• Wear a medical alert bracelet or necklace. These bracelets and necklaces let others know that you have a food allergy if you have a reaction and you cannot communicate.
• Be careful at restaurants. Be certain your server or chef is aware that you absolutely can't eat the food you're allergic to. Also, make sure food isn't prepared on surfaces or in pans that contained the food you're allergic to.
• When in doubt, say no thanks. At restaurants and social gatherings, there's often a risk of being exposed to a food allergen. People may not understand that a food allergy is serious or that a tiny amount of food can cause a severe reaction.

If your child has a food allergy, work with your child, family members, sitters, teachers, coaches, and others who care for or supervise your child.

• Explain food allergy symptoms. Teach the adults who spend time with your child how to recognize signs and symptoms of an allergic reaction. Emphasize that an allergic reaction can be life-threatening and requires immediate action.
• Educate your child. Talk with your child about what foods to avoid. Make sure your child also knows to ask for help right away in case of a food reaction. Make sure an older child knows how to take epinephrine.
• Write an action plan. Your plan should describe what steps to take if your child has an allergic reaction to food. Make sure it states how and when to use an epinephrine autoinjector or nasal spray and when to get emergency care. Provide a copy of the plan to your child's school nurse, classroom teacher, coaches and others who provide supervision.
• Have your child wear a medical alert bracelet or necklace. This alert lists your child's allergy symptoms and explains how others can provide first aid in an emergency.
• Talk about food avoidance. Talk with caregivers and teachers about classroom practices of hand-washing and cleaning of surfaces that can help prevent exposure to allergens.

Coping and support

A food allergy can be a source of ongoing concern that affects life at home, school and work. Daily activities that are easy for most families, such as grocery shopping and meal preparation, can become stressful for families and caregivers living with food allergies.

Keep these strategies in mind to help manage your or your child's food allergy-related stress:

• Connect with others. The opportunity to discuss food allergies and exchange information with others who share your concerns can be very helpful. Many internet sites and nonprofit organizations offer information and forums for discussing food allergies. The Food Allergy Research & Education (FARE) website can direct you to support groups and events in your area.
• Address bullying. Children are sometimes bullied at school because of their food allergies. Discussing your child's allergy with school personnel greatly reduces your child's risk of being a bullying target.

Preparing for your appointment

Because appointments can be brief, and because there's often a lot of ground to cover, it's a good idea to be well prepared. Here's some information to help you get ready and know what to expect.

• Write down any symptoms you've had, including any that may seem unrelated to your concerns about food.
• Write down key personal information, including any major stresses or recent life changes.
• Make a list of all medicines, vitamins and supplements that you or your child is taking, as well as the doses and reasons for taking each one.
• Take a family member or friend along, if possible. Sometimes it can be difficult to remember all the information provided to you during an appointment. Someone who accompanies you may recall something that you missed or forgot.
• Write down questions to ask your care team.

Your time is limited, so preparing a list of questions will help you make the most of your time together. List your questions from most important to least important in case time runs out. Some basic questions to ask include:

• Are my symptoms likely caused by a food allergy or another condition?
• What kinds of tests do I need?
• Is my condition likely temporary or long-lasting?
• What types of treatment are available?
• I have other health conditions. How can I best manage these conditions together?
• Should I see a specialist? What will that cost, and will my insurance cover seeing a specialist?
• Is there a generic alternative to the medicine you're prescribing me?
• Do you have any printed material that I can take home with me? What websites do you recommend visiting?

If your child is seeing the health professional for a food allergy, you also may want to ask:

• Is my child likely to outgrow this allergy?
• Are there alternatives to the food or foods that trigger my child's allergy symptoms?
• How can I help keep my child with a food allergy safe at school?

In addition to the questions that you've prepared to ask your healthcare professional, don't hesitate to ask other questions during your appointment.

What to expect from your doctor

Your healthcare professional is likely to ask you a few questions. Being ready to answer them may save time to go over any points you want to spend more time on. You may be asked:

• What were your symptoms?
• How long did symptoms last?
• What did you eat before the reaction?
• How long did it take symptoms to appear after eating suspect food?
• How much food did you eat before the reaction?
• Was the suspect food cooked or raw?
• Do you know how the food was prepared?
• Have you eaten the suspect food in the past without a reaction?
• Did you take any allergy medicines you can buy without a prescription such as antihistamines?
• Do you or someone else in the family have allergies or asthma?

What you can do in the meantime

If you suspect you have a food allergy, avoid the food altogether until your appointment. If you do eat the food and have a mild reaction, antihistamines you can buy without a prescription may help relieve symptoms. If you have a more severe reaction and any symptoms of anaphylaxis, seek emergency help.