Peanut Allergy – Symptoms and Causes


Peanut allergy is one of the most common causes of severe allergy attacks. For some people with peanut allergies, even small amounts of peanuts can cause a severe, even life-threatening reaction (anaphylaxis).

Peanut allergy has increased in children. Even if you or your child has only had a mild allergic reaction to peanuts, it’s important to tell your doctor. There is always a risk of a more serious future reaction.



An allergic reaction to peanuts usually occurs within minutes of exposure. Peanut allergy signs and symptoms may 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
  • Throat tightening
  • Shortness of breath or wheezing
  • Runny nose

Anaphylaxis: a life-threatening reaction

Peanut allergy is the most common cause of foodborne anaphylaxis, a medical emergency that requires treatment with an epinephrine (adrenaline) auto-injector (EpiPen, Auvi-Q, others) and a emergency room trip.

Signs and symptoms of anaphylaxis can include:

  • Airway constriction
  • Swelling of the throat that makes it difficult to breathe
  • A severe drop in blood pressure (shock)
  • fast pulse
  • Dizziness, lightheadedness, or loss of consciousness

When to consult a doctor

Tell your doctor if you’ve had any signs or symptoms of peanut allergy.

Seek emergency treatment if you have a severe reaction to peanuts, especially if you have signs or symptoms of anaphylaxis. Call 911 or your local emergency number if you or anyone else experiences severe dizziness, severe difficulty breathing, or loss of consciousness.


Peanut allergy occurs when your immune system mistakenly identifies peanut protein as something harmful. Direct or indirect contact with peanuts causes your immune system to release symptom-causing chemicals into your bloodstream.

Exposure to peanuts can happen in different ways:

  • Direct contact. The most common cause of peanut allergy is eating peanuts or foods containing peanuts. Sometimes direct skin contact with peanuts can trigger an allergic reaction.
  • Cross contact. It is the unintentional introduction of peanuts into a product. It is usually the result of food being exposed to peanuts during processing or handling.
  • Inhalation. An allergic reaction may occur if you inhale dust or aerosols containing peanuts from a source such as peanut flour or peanut oil cooking spray.

Risk factors

It is not known why some people develop allergies while others do not. However, people with certain risk factors have a higher chance of developing peanut allergy.

Peanut allergy risk factors include:

  • Age. Food allergies are more common in children, especially toddlers and infants. As you age, your digestive system matures and your body is less likely to react to foods that trigger allergies.
  • Past allergy to peanuts. Some peanut-allergic children outgrow it. However, even if you seem to have outgrown the peanut allergy, it can reoccur.
  • Other allergies. If you are already allergic to one food, you are at increased risk of becoming allergic to another. Likewise, having another type of allergy, such as hay fever, increases your risk of having a food allergy.
  • Family members with allergies. You are at increased risk for peanut allergy if other allergies, especially other types of food allergies, are common in your family.
  • Atopic dermatitis. Some people with atopic dermatitis (eczema) also have a food allergy.


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


According to recent studies, there is strong evidence that introducing peanuts to at-risk babies as young as 4-6 months old can reduce their risk of developing food allergies by up to 80%. Babies at risk for peanut allergy include those with mild to severe eczema, egg allergy, or both. Before introducing peanuts to your baby, discuss the best approach with your child’s doctor.

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