Peanut allergy is common and often appears in the first years of life. While many children outgrow allergies to other foods such as milk or eggs, most kids don't outgrow peanut allergy as they get older.

An allergic reaction to peanuts can range from a minor irritation to a life-threatening reaction called anaphylaxis. Even people who have only had a mild reaction in the past are at risk of a more serious future reaction.

If your child has a peanut allergy — or you're an adult who has had a reaction — tell your doctor about it, even if it was minor. Tests can help confirm a peanut allergy, so you can take steps to avoid future and potentially worse reactions.

An allergic response to peanuts usually occurs within minutes after exposure, and signs and symptoms range from mild stomach or skin reactions to anaphylaxis, a life-threatening reaction that can constrict the airways and block breathing.

Common symptoms
Signs and symptoms of peanut allergy 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 chest
• Shortness of breath or wheezing
• Runny or stuffy nose

Anaphylaxis
Peanut allergy is the most common cause of anaphylaxis, a medical emergency that requires treatment with an epinephrine (adrenaline) injector (EpiPen, Twinject) and a trip to the emergency room. Signs and symptoms start soon after consuming peanuts and can include:

• Constriction of airways, including a swollen throat that makes it difficult to breathe
• Shock, with a severe drop in blood pressure
• Rapid pulse
• Dizziness, lightheadedness or loss of consciousness

Peanut allergy occurs when your immune system develops allergy-type antibodies to peanut proteins. Your immune system mistakenly identifies the proteins as something harmful. The next time you come in contact with peanuts, these antibodies recognize it and signal your immune system to release chemicals such as histamine into your bloodstream, which leads to the signs and symptoms of an allergic response. Scientists aren't sure why some people become allergic to peanuts and others don't.

Exposure to peanuts can occur in three ways:

• Direct contact. The most common cause of peanut allergy is eating peanuts or peanut-containing foods. Sometimes direct skin contact with peanuts can trigger an allergic reaction.
• Cross-contact. This is the unintended introduction of peanuts into a product. It's generally the result of exposure to peanuts during processing or handling of a food product.
• Inhalation. An allergic reaction may occur if you inhale dust or aerosols containing peanuts, such as that of peanut flour or peanut oil cooking spray.

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:

• Family members with allergies. You're at increased risk of peanut allergy if other allergies, especially other types of food allergies, are common in your family.
• Past allergy to peanuts. About one in five children with peanut allergy outgrow it. However, even if you seem to have outgrown peanut allergy, it may recur.

For unknown reasons, the number of children with allergies — including peanut allergy — is steadily increasing. Based on the fact that urban children are more likely to develop allergies than rural children, the "hygiene hypothesis" proposes that children who are exposed to as many microbes or allergy-causing substances at an early age may develop immune systems that are more tolerant — and less likely to react to peanuts or other potential allergens. Other experts suggest that the increased incidence of peanut allergy may reflect an increased awareness and reporting of food allergies or changes in the way peanuts are processed.

Talk to your doctor if you think you're allergic to peanuts or if you have peanut allergy symptoms. If possible, see your doctor while you have symptoms.

Seek emergency treatment for a severe reaction. If you or your child is having an allergic reaction, you should use an epinephrine autoinjector (EpiPen, Twinject) immediately and seek emergency treatment if signs and symptoms include:

• Trouble breathing
• Tightness in the throat
• Feeling lightheaded or dizzy
• Loss of consciousness

Your doctor will want to know your signs and symptoms and may want to conduct a physical examination to identify or exclude other medical problems. He or she may also recommend consultation with an allergist, who may request one or both of the following tests:

• Skin prick test. With this test, your skin is pricked and exposed to small amounts of the proteins found in peanuts to see if you have a skin response. If you're allergic, you develop a raised bump (hive) at the test location on your skin. Allergy specialists usually are best equipped to perform allergy skin tests.
• Blood test. A blood test (sometimes called the radioallergosorbent test, or RAST) can measure your immune system's response to peanuts by measuring the amount of certain antibodies in your bloodstream, known as immunoglobulin E (IgE) antibodies. A blood sample is sent to a medical laboratory, where it can be tested for evidence of sensitivity to peanuts.

Is it peanut allergy? Or is it peanut intolerance?
Not all adverse reactions to peanuts are caused by an allergic reaction. It can be difficult to know whether you are allergic or intolerant to peanuts.

• If you have peanut intolerance, you usually can eat small amounts of peanuts with only mild symptoms, such as indigestion or heartburn, or no reaction at all. A peanut intolerance doesn't involve your immune system.
• An allergy involves an immune system response. Even a tiny amount of peanuts may trigger a serious allergic reaction. Tests can help determine whether you have true peanut allergy.

The only way to prevent an allergic reaction is to avoid peanuts and peanut proteins altogether. But peanuts are common, and despite your best efforts, you or your child is likely to come into contact with peanuts at some point.  

While most reactions to peanuts are not life-threatening, it's important to be prepared for a severe reaction. For an anaphylactic reaction, an emergency injection of adrenaline (epinephrine) and a trip to the emergency room are necessary. If your doctor thinks you may be at risk of a severe reaction, you'll probably need to carry injectable epinephrine (EpiPen, Twinject) with you at all times.

Medications, such as antihistamines, may reduce the mild symptoms of peanut allergies. These drugs can be taken after exposure to peanuts to help relieve itching or hives. However, antihistamines are not sufficient to treat severe, life-threatening reactions.

The best way to prevent an allergic reaction to peanuts is to know and avoid foods that cause signs and symptoms. In some foods, peanuts may be well hidden. This is especially true in restaurants and in other social settings.

If you know you have peanut allergy, follow these steps:

• Be sure to read food labels carefully, and avoid foods that may have come in contact with peanuts. Manufactured foods are required to clearly state whether foods contain any peanuts, and if they were produced in factories that also process peanuts.
• If you've already had a severe reaction to peanuts, wear a medical alert bracelet or necklace.
• Talk with your doctor about carrying emergency medications.

Avoid foods that often contain peanuts
Peanuts are common, and avoiding foods that contain them can be a challenge. 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 molding confection made of nuts, egg whites and sugar)

Less obvious foods may contain peanut proteins. Some examples include:

• Nougat
• Salad dressings
• Chocolate candies, nut butters (such as almond butter) and sunflower seeds are sometimes processed with equipment also used for peanuts
• Cultural foods including African, Chinese, Indonesian, Mexican, Thai and Vietnamese dishes often contain peanuts
• Foods sold in bakeries and ice-cream shops may come in contact with peanuts
• Arachis oil, another name for peanut oil

Take steps to keep your child safe
If your child has peanut allergy, these precautions can help:

• Notify key people that your child has peanut allergy. Talk with child care providers, school personnel, parents of your child's friends, and other adults who regularly interact with your child. Emphasize that an allergic reaction can be life-threatening and requires immediate action. Make sure that your child also knows to ask for help right away if he or she reacts to peanuts.
• Make sure your child's epinephrine autoinjector is always available. If your child has had a serious allergic reaction to peanuts, he or she may be prescribed an emergency epinephrine injector (EpiPen, Twinject). An injection of epinephrine (adrenaline) can immediately reduce the severity of a potentially life-threatening anaphylactic reaction. Epinephrine is good for about 18 months. Be sure to replace epinephrine nearing the expiration date. Expired epinephrine may not be effective.
• Explain peanut allergy symptoms. Teach the adults who spend time with your child how to recognize signs and symptoms of an allergic reaction to peanuts.
• Write an action plan. Your plan should describe how to care for your child when he or she has an allergic reaction to peanuts. Provide a copy of the plan to your child's school and to others who care for and supervise your child.
• Have your child wear a medical alert bracelet or necklace. This alert lists your child's name, type of allergy and the triggers that cause a reaction. It may also include brief emergency instructions.
• Discourage your child from sharing foods. It's common for kids to share snacks and treats. However, during times of fun your child may forget about food allergies or sensitivities. If your child is allergic to peanuts, encourage him or her to refrain from eating food from others.