Diagnosis
There's no perfect test used to confirm or rule out a food allergy. Your healthcare team will consider a few factors before making a diagnosis. These factors include:
- Your symptoms. Give your care team a detailed history of your or your child's symptoms — which foods, and how much, seem to cause problems.
- Your family history of allergies. Also share information about members of your family who have allergies of any kind.
- A physical examination. A careful exam can often identify or exclude other medical problems.
A skin test. A skin prick test can determine whether you may react to a particular food. In this test, a small amount of the suspected food is placed on the skin of your forearm or back. A doctor or another healthcare professional then pricks your skin to allow a tiny amount of the substance beneath your skin surface.
If you're allergic to a particular substance being tested, you develop a raised bump or reaction. However, a positive reaction to this test alone isn't enough to confirm a food allergy.
A blood test. A blood test can measure your immune system's response to particular foods by measuring the allergy-related antibody known as immunoglobulin E (IgE).
For this test, a blood sample taken in your care professional's office is sent to a medical laboratory. It will then be tested for foods that could have caused an allergic reaction.
Elimination diet. You may be asked to eliminate suspect foods for a week or two and then add the food items back into your diet one at a time. This process can help link symptoms to specific foods. However, elimination diets aren't foolproof.
An elimination diet can't tell you whether your reaction to a food is a true allergy instead of a food sensitivity. Also, if you've had a severe reaction to a food in the past, an elimination diet may not be safe.
- Oral food challenge. During this test, done in a healthcare professional's office, you'll be given small but increasing amounts of the food suspected of causing your symptoms. If you don't have a reaction during this test, you may be able to include this food in your diet again.
Treatment
One way to avoid an allergic reaction is to avoid the foods that cause symptoms. However, despite your best efforts, you may come into contact with a food that causes a reaction.
For a minor allergic reaction, prescribed antihistamines or those available without a prescription may help reduce symptoms. These drugs can be taken after exposure to an allergy-causing food to help relieve itching or hives. However, antihistamines can't treat a severe allergic reaction.
For a severe allergic reaction, you may need an emergency injection of epinephrine and a trip to the emergency room. Many people with allergies carry an epinephrine autoinjector (Adrenaclick, EpiPen). This device is a combined syringe and concealed needle that injects a single dose of medicine when pressed against your thigh.
If you've been prescribed an epinephrine autoinjector:
- Be sure you know how to use the autoinjector. Also, make sure the people closest to you know how to give the drug — if they're with you in an anaphylactic emergency, they could save your life.
- Carry it with you at all times. It may be a good idea to keep an extra autoinjector in your car or in your desk at work.
- Always be sure to replace epinephrine before its expiration date or it may not work properly.
Emerging treatments
There is ongoing research to find better treatments to reduce food allergy symptoms and prevent allergy attacks. However, there is currently no proven treatment that can prevent or completely relieve symptoms.
The U.S. Food and Drug Administration recently approved omalizumab (Xolair) to help reduce allergic reactions to multiple foods. Omalizumab is a type of drug called a monoclonal antibody. This medicine is approved for certain adults and children 1 year old or older.
Omalizumab doesn't prevent all allergic reactions to food. It also hasn't been tested to see if people with food allergy can add food allergens into their diets. Instead, omalizumab may be used as a preventive measure. Regular injections of omalizumab may reduce food allergy reactions if small amounts of a food allergen are eaten by mistake.
The first oral immunotherapy drug, Peanut (Arachis hypogaea) Allergen Powder-dnfp (Palforzia), also has been approved to treat children ages 4 to 17 years old with a confirmed peanut allergy. This medicine isn't recommended for people with uncontrolled asthma or certain conditions, including eosinophilic esophagitis.
Additional treatments currently being studied as treatments for food allergy are oral immunotherapy and sublingual immunotherapy. With these treatments, you are exposed to small doses of your food allergen. You swallow the small doses, or the doses are placed under your tongue. The dose of the allergy-provoking food is gradually increased.
Lifestyle and home remedies
One of the keys to preventing an allergic reaction is to completely avoid the food that causes your symptoms.
Don't assume. Always read food labels to make sure they don't contain an ingredient you're allergic to. Even if you think you know what's in a food, check the label. Ingredients sometimes change.
Food labels are required to clearly list whether the food products contain any common food allergens. Read food labels carefully to avoid the most common sources of food allergens: milk, eggs, peanuts, tree nuts, fish, shellfish, soy and wheat.
When in doubt, say no thanks. At restaurants and social gatherings, you're always taking a risk that you might eat a food you're allergic to. Many people don't understand the seriousness of an allergic food reaction and may not realize that a tiny amount of a food can cause a severe reaction in some people.
If you have any suspicion at all that a food may contain something you're allergic to, don't eat it.
Involve caregivers. If your child has a food allergy, enlist the help of relatives, babysitters, teachers and other caregivers. Make sure that they understand how important it is for your child to avoid the allergy-causing food and that they know what to do in an emergency.
It's also important to let caregivers know what steps they can take to prevent a reaction in the first place, such as careful hand-washing and cleaning any surfaces that might have come in contact with the allergy-causing food.
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 occasions of stress 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. Some are specifically for parents of children with food allergies. The Food Allergy Research & Education website can direct you to support groups and events in your area.
- Educate those around you. Make sure family and caregivers, including babysitters and school staff, have a thorough understanding of your child's food allergy.
- 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 what to expect.
- Write down any symptoms you've had, including any that may seem unrelated to the reason for which you scheduled the appointment.
- Write down key personal information, including any major stresses or recent life changes.
- Make a list of all medicines, vitamins and supplements that you're taking.
- 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:
- Is my condition likely caused by a food allergy or another reaction?
- What kinds of tests do I need?
- Is my condition likely temporary or long lasting?
- What types of treatment are available, and which do you recommend?
- What are the alternatives to the primary approach that you're suggesting?
- I have these other health conditions. How can I best manage these conditions together?
- Are there any dietary restrictions that I need to follow?
- 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 doctor for a food allergy, you may also 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 doctor, don't hesitate to ask questions during your appointment.
What to expect from your doctor
Your doctor 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:
- When did you begin experiencing symptoms?
- How severe were your symptoms?
- How long did it take symptoms to appear after eating the food you suspect you're allergic to?
- Did you take any nonprescription allergy medications such as antihistamines, and if so, did they help?
- Does your reaction always seem to be triggered by a certain food?
- How much food did you eat before the reaction?
- Was the food that caused the reaction cooked or raw?
- Do you know how the food was prepared?
- What, if anything, seems to improve your symptoms?
- What, if anything, appears to worsen your symptoms?
What you can do in the meantime
If you suspect you have a food allergy, avoid exposure to the food altogether until your appointment. If you do eat the food and have a mild reaction, nonprescription antihistamines may help relieve symptoms. If you have a more severe reaction and any symptoms of anaphylaxis, seek emergency help.