An allergic response to peanuts usually occurs within minutes after exposure, and symptoms range from mild to severe. 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 food-induced anaphylaxis, a medical emergency that requires treatment with an epinephrine (adrenaline) injector (EpiPen, Twinject) and a trip to the emergency room.
Anaphylaxis signs and symptoms can include all of the above, plus:
- Constriction of airways
- Swelling of your throat that makes it difficult to breathe
- A severe drop in blood pressure (shock)
- Rapid pulse
- Dizziness, lightheadedness or loss of consciousness
When to see a doctor
Talk to your doctor if you think you could be allergic to peanuts, especially if you had a severe reaction.
Seek emergency treatment if you have a severe reaction to peanuts, especially if you have any signs or symptoms of anaphylaxis. Call 911 or your local emergency number if you or someone else displays severe dizziness, severe trouble breathing or loss of consciousness.
Peanut allergy occurs when your immune system mistakenly identifies peanut proteins as something harmful. When you have direct or indirect contact with peanuts, your immune system releases symptom-causing chemicals into your bloodstream. It isn't known exactly why some people become allergic to peanuts and others don't.
Exposure to peanuts can occur in different 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 a food being exposed to peanuts during processing or handling.
- 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.
Food allergy vs. food intolerance
In some cases, what may appear to be a food allergy may actually be a food intolerance. Unlike a true food allergy, a food intolerance doesn't involve the immune system. With a true food allergy, even tiny amounts of the food can cause a severe reaction. In most cases, someone who has a food intolerance can eat small amounts of the food with only mild symptoms, such as indigestion or heartburn.
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.
Food allergy risk factors include:
- Age. Food allergies are most common in children, especially toddlers and infants. As you grow older, your digestive system matures, and your body is less likely to react to food that triggers allergies.
- Past allergy to peanuts. Some children with peanut allergy outgrow it. However, even if you seem to have outgrown peanut allergy, it may recur.
- Other allergies. If you're already allergic to one food, you may be 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're at increased risk of peanut allergy if other allergies, especially other types of food allergies, are common in your family.
- Atopic dermatitis. Some people with the skin condition atopic dermatitis (eczema) also have a food allergy.
While some people think food allergies are linked to childhood hyperactivity and to arthritis, there's no evidence to support this.
Complications of food allergy can include:
- Need for special precautions. Because allergic reactions to peanuts are severe for many people, avoiding peanuts altogether is very important. This requires taking a number of steps to prevent accidental exposure.
- Anaphylaxis. Children and adults who've had a severe peanut allergy are especially at risk of having this life-threatening reaction.