Overview

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.

Symptoms

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 a kind of 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.

Causes

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.

Risk factors

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

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.

Prevention

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.

By Mayo Clinic Staff