Peanut allergy is a condition that causes the body's germ-fighting immune system to react to peanuts. It's one of the most common causes of a life-threatening allergic reaction to food. This life-threatening reaction is known as anaphylaxis.

Peanut allergy has been increasing in children. Even if you or your child has shown only a mild reaction to peanuts, it's important to talk to a healthcare professional. There is still a risk of a more serious future reaction.

An allergic response to peanuts usually occurs within minutes after exposure. Peanut allergy signs and symptoms can include:

• Skin reactions, such as hives, redness or swelling.
• Itching or tingling in or around the mouth and throat.
• Digestive problems, such as diarrhea, stomach cramps, nausea or vomiting.
• Tightening of the throat.
• Shortness of breath or wheezing.
• Runny nose.

Anaphylaxis: A life-threatening reaction

Peanut allergy is the most common cause of anaphylaxis due to food. This medical emergency requires treatment with an epinephrine autoinjector (EpiPen, Auvi-Q, others) and a trip to the emergency room. Epinephrine is also called adrenaline.

Anaphylaxis signs and symptoms can include:

• Constriction of airways.
• Swelling of the lips, tongue and throat that makes it hard to breathe.
• A severe drop in blood pressure, also known as shock.
• Rapid pulse.
• Dizziness, lightheadedness or loss of consciousness.

When to see a doctor

Talk to your care team if you have had any signs or symptoms of peanut allergy. Seek emergency treatment if you have a severe reaction to peanuts.

Call, or have someone else call 911 or your local emergency number if you have any signs or symptoms of anaphylaxis such as:

• Severe dizziness.
• Severe trouble breathing.
• Loss of consciousness.

Peanut allergy occurs when the immune system flags peanut proteins as harmful. When exposed to peanuts, the immune system releases symptom-causing chemicals into the bloodstream. These chemicals cause an allergic reaction.

Direct and cross-contact with peanuts could cause a reaction:

• Direct contact. The most common cause of peanut allergy is eating peanuts or foods that contain peanuts.
• Cross-contact. This happens when peanuts get into a product by mistake. It often happens when food is exposed to peanuts during processing or handling.
• Inhalation. Breathing in dust or aerosols containing peanuts, such as peanut flour, may cause an allergic reaction.

It isn't clear why some people develop allergies while others don't. However, people with certain risk factors have a greater chance of developing peanut allergy.

Peanut allergy risk factors include:

• Age. Food allergies are most common in children, especially toddlers and infants. As a person grows, the digestive system matures. Then the body is less likely to react to food that triggers allergies.
• Past allergy to peanuts. Some children with peanut allergy outgrow it, though it can recur. So be cautious even if you seem to have outgrown peanut allergy.
• Other allergies. If you're already allergic to one food, you have a higher risk of being allergic to another. Also, having another type of allergy, such as hay fever, raises your risk of having a food allergy.
• Family members with allergies. Your risk of peanut allergy is higher if other allergies are common in your family, especially other food allergies.
• Atopic dermatitis. Some people with the skin condition atopic dermatitis, also called eczema, have a food allergy as well.

Complications of peanut allergy can include anaphylaxis. Children and adults who have a severe peanut allergy are especially at risk of having this life-threatening reaction.

Studies have shown a strong link between early peanut exposure and lower food allergy risk. In the studies, peanuts were introduced to high-risk babies and children from 4 months to 3 years old. By doing so, their food allergy risk was reduced up to 80%. Children at risk of peanut allergy include those with mild to severe eczema, egg allergy, or both. Before introducing your child to peanuts, discuss the best approach with your child's healthcare professional.

Talking with your healthcare team about your symptoms and medical history starts the process of diagnosis. A physical exam usually follows and these next steps may be needed:

• Food diary. Your care team may ask you to keep a food diary of your eating habits, symptoms and medicines.
• Skin test. A small amount of food or other substance is placed on your skin. Then, your skin is pricked with a needle. If you're allergic to that substance, you'll develop a raised bump or reaction.
• Blood test. A blood test can measure your immune system's response to certain foods. It checks the amount of allergy-type antibodies in your bloodstream, also known as immunoglobulin E (IgE) antibodies.
• Elimination diet. Your team may suggest an elimination diet if you could be allergic to more foods in addition to peanuts. You might be asked to stop eating peanuts or other suspect foods for a week or two. Then, you'll add the food items back into your diet one at a time. This process can help link symptoms to certain foods. If you've had a severe reaction to foods, this method can't safely be used.

All these sources may help confirm a peanut allergy. Or they may point to another cause such as food intolerance.

The standard approach to care for peanut allergy is to avoid foods that contain peanuts. Yet researchers continue to study different therapies that will lessen the chance of severe reactions, including anaphylaxis.

Immunotherapy

Immunotherapy is a treatment that is meant to train the immune system not to react to certain triggers. This process also is known as desensitization. These therapies may not cure peanut allergy, and they cannot replace emergency treatment for anaphylaxis. However, they may reduce the risk of future severe reactions if contact with peanuts happens.

Immunotherapy for peanut allergy includes oral immunotherapy (OIT). In OIT, doses of food with peanuts are given to those with or at risk of developing a peanut allergy. These doses are slowly increased over time until the highest tolerated dose is reached.

The medicine Peanut Allergen Powder-dnfp (Palforzia) is an FDA-approved form of oral immunotherapy. It is meant to treat children ages 4 to 17 years with a confirmed peanut allergy. This treatment isn't recommended for people with uncontrolled asthma or certain conditions, including eosinophilic esophagitis.

Antibodies

Antibody treatment is another method. This medicine is given through injection. Although antibody treatments also involve the immune system, they work differently from other forms of immunotherapy.

These medicines work by binding to a special protein in the bloodstream that causes a certain allergic reaction. These protective proteins are called antibodies. Once bound to the antibody, the medicine makes the immune system much less sensitive to a certain allergic trigger. Antibody treatments for peanut allergy include omalizumab (Xolair).

Being prepared for a reaction

The only way to prevent a reaction is to avoid peanuts and peanut products altogether. However, peanuts are common. Even when you try your best, you're likely to come into contact with peanuts at some point.

For a severe allergic reaction, you may need an emergency injection of epinephrine and a visit to the emergency room. Many people with allergies carry an epinephrine autoinjector. This device is a syringe and hidden needle that injects a single dose of medicine when pressed against your thigh.

Know how to use your autoinjector

If your doctor has prescribed an epinephrine autoinjector:

• Carry it with you at all times. It may be a good idea to keep an extra autoinjector in your car and in your desk at work.
• Always replace it before its expiration date. Out-of-date epinephrine may not work properly.
• Ask your doctor to prescribe a backup autoinjector. If you misplace one, you'll have a spare.
• Know how to operate it. Ask your healthcare team to show you. Also, make sure the people closest to you know how to use it. If someone with you can give you a shot, that person could save your life.
• Know when to use it. Talk to a healthcare professional about how to know when you need a shot. If you're not sure, it's usually better to go ahead and use the emergency epinephrine.

One of the keys to preventing an allergic reaction is knowing how to avoid the food that causes your symptoms. Follow these steps:

• Never assume that a food doesn't contain peanuts. Peanuts may be in foods that surprise you. Always read labels on processed foods to make sure they don't contain peanuts or peanut products. Processed foods are required to clearly state if foods contain any peanuts. Also, labels must state if foods were produced in factories that process peanuts.

  Even if you think that you know what's in a food, check the label. Ingredients may change.

• Don't ignore a label that says a food was produced in a factory that processes peanuts. Most people with a peanut allergy need to avoid all products that could contain peanuts, even trace amounts.
• When in doubt, say "no thanks." At restaurants and social gatherings, there's always a risk of eating peanuts by accident. Many people don't understand how serious an allergic food reaction is. They may not know that a tiny amount of a food can cause a severe reaction. If you are at all worried that a food may contain something you're allergic to, don't try it.
• Be prepared for a reaction. Talk with your doctor about carrying emergency medicines in case of a severe reaction.

Avoiding foods that contain peanuts

Peanuts are common. Avoiding foods that contain them can be hard. The following foods often contain peanuts:

• Ground or mixed nuts.
• Baked goods, such as cookies and pastries.
• Ice cream and frozen desserts.
• Energy bars.
• Cereals and granola.
• Grain breads.
• Marzipan, a candy made of nuts, egg whites and sugar.

Some foods that may contain peanuts or peanut proteins are less obvious. They might have been made with peanuts or come in contact with them during processing. Some examples include:

• Nougat.
• Salad dressings.
• Chocolate candies, nut butters such as almond butter and sunflower seeds.
• Global foods including African, Chinese, Indonesian, Mexican, Thai and Vietnamese dishes.
• Foods sold in bakeries and ice cream shops.
• Arachis oil, another name for peanut oil.
• Pet food.

If your child has peanut allergy, take these steps to help keep your child safe:

• Involve caregivers. Ask relatives, babysitters, teachers and other caregivers to help. Teach the adults who spend time with your child how to recognize signs and symptoms of an allergic reaction to peanuts. Emphasize that an allergic reaction can be life-threatening and requires immediate action.

  Also, make sure that your child knows to ask for help right away in case of an allergic reaction.

• Use a written plan. Write down the steps to take in case of an allergic reaction. Include the order and doses of all medicines to be given. List contact information for family members and healthcare providers. Give a copy of the plan to family members, teachers and others who care for your child.
• Discourage your child from sharing foods. It's common for kids to share snacks and treats. However, while playing, your child may forget about food allergies or sensitivities. If your child is allergic to peanuts, encourage your child not to eat food from others.
• Make sure your child's epinephrine autoinjector is always available. An injection of epinephrine needs to be given right away to reduce the chance of anaphylaxis. Make sure caregivers and family members know about your child's emergency medicine. They should know where the autoinjector is located, when it may be needed and how to use it.
• Make sure your child's school has a food allergy management plan. Guidelines are available to create policies and procedures. Staff should have access to an epinephrine injector and be trained how to use it.
• Have your child wear a medical alert bracelet or necklace. This will help your child get the right treatment if communication isn't possible during a severe reaction. The alert will include your child's name and the type of food allergy. Also, it may list brief emergency instructions.

If you have peanut allergy, do the following:

• Always carry your epinephrine autoinjector.
• Wear a medical alert bracelet or necklace.

To get the most from your appointment, it's a good idea to be well prepared. Here's some information to help you get ready for your appointment and know what to.

• Describe your symptoms. Be ready to tell your doctor what happened after you ate peanuts or food that contains peanuts. Note how long it took for a reaction to occur. Try to recall how many peanuts you ate. Or how much you ate of a peanut-containing food that triggered your symptoms.
• Make a list of all the medicines you're taking. Include vitamins or supplements.
• Take a family member or friend along. Sometimes it can be difficult to recall all the information provided to you during an appointment. If someone can join you, that person may remember something that you missed or forgot.
• Write down any questions you have.

Some basic questions to ask include:

• Are my symptoms likely caused by peanut allergy?
• What else might be causing my symptoms?
• What tests do I need?
• What's the best treatment?
• Should I see a specialist?
• Is there a generic version of the medicine you're prescribing?
• Are there brochures or other printed material that I can take with me? What websites do you recommend?
• Do I need to carry an epinephrine autoinjector?

If your child is seeing a healthcare professional for a peanut allergy, you also may want to ask:

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

Don't hesitate to ask any other questions.

What to expect from your doctor

A healthcare professional is likely to ask you a number of questions, including:

• When did you begin noticing symptoms?
• After eating peanuts, how long did it take for symptoms to appear?
• What quantity of peanuts did you eat?
• Did you take any nonprescription allergy medications, such as antihistamines, and if so, did they help?
• Does your reaction seem to be triggered only by peanuts or by other foods as well?
• How severe are your symptoms?
• 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 think you have a peanut allergy, avoid contact with peanuts until you can meet with your care team. If you have a severe reaction, seek emergency help.