3 Causes of Peanut Allergy and How to Prevent Reactions

Researchers are still working to fully understand why some people develop peanut allergies while others do not. Current evidence suggests that several factors may contribute to the development of a peanut allergy, including genetics, environmental exposure, and food manufacturing practices.

Genetics and family history

Genetics may play a role in peanut allergies. Some studies suggest that certain genetic variations could increase the likelihood of developing food allergies, including peanut allergies. However, having a family history of allergies does not guarantee that someone will develop a peanut allergy themselves. Environmental and lifestyle factors also appear to contribute.

Frequent exposure to peanuts

Peanuts are widely used in packaged and prepared foods, which may increase the chances of exposure over time. Peanut ingredients can appear in foods like baked goods, cereals, sauces, soups, snack bars, and candy. Some products may also contain peanut oil or be processed alongside peanut-containing foods.

Researchers continue to study whether early or repeated exposure to peanuts may influence allergy development in some individuals.

Cross-contact during food production

Cross-contact can happen when foods are prepared or processed on shared equipment that also handles peanuts. Even small traces of peanut protein may trigger allergic reactions in sensitive individuals.

Because of this, carefully reading food labels is important for people with peanut allergies. Many packaged foods include allergen warnings such as “may contain peanuts” or “processed in a facility that also processes peanuts.”

Is a peanut allergy the same as a tree nut allergy?

Peanuts belong to the legume family. Therefore, someone who is allergic to peanuts may or may not also be allergic to tree nuts. Peanuts and tree nuts share some common proteins, which is why you can be allergic to one or both.

Common tree nuts include:

• Almonds
• Hazelnuts
• Walnuts
• Brazil nuts
• Macadamia nuts
• Pecans
• Pistachios
• Cashews

Still, some people who react to peanuts can eat other nuts without any issues. You would have to test for a tree nut allergy separately from peanuts to determine if you were allergic to both.

Peanut allergy symptoms can range from mild to severe and may appear within minutes after exposure to peanuts. In some cases, symptoms may affect the skin, digestive system, respiratory system, or multiple parts of the body at once.

Common peanut allergy symptoms include [5]:

• Hives or skin rash
• Itchy or swollen lips, mouth, or throat
• Wheezing or difficulty breathing
• Stomach pain, nausea, vomiting, or diarrhea
• Watery or itchy eyes
• Dizziness or fainting

In severe cases, peanut exposure can lead to anaphylaxis, a life-threatening allergic reaction that requires immediate emergency medical attention. Symptoms of anaphylaxis may include severe breathing difficulty, throat swelling, a rapid drop in blood pressure, or loss of consciousness.

A healthcare provider may recommend carrying epinephrine, such as an auto-injector, if you have a history of severe allergic reactions.

Diagnosing food allergies can be tricky. Ingredients in certain products aren’t always clear or properly disclosed. Furthermore, different people might experience different symptoms in response to an allergen.

If you think you or your child may be allergic to peanuts, a healthcare provider may recommend one or more of the following diagnostic methods: [6]

• Skin test – In a skin test, a tiny amount of peanut allergen is placed on your skin. Your skin is then lightly pricked with a small needle. If you’re allergic to peanuts, your skin may develop a raised red bump at the site of the prick.
• Blood test – A blood test can also help diagnose a peanut allergy. A small sample of your blood is collected and analyzed for immunoglobulin E (IgE) antibodies, which may indicate an allergic response.
• Supervised food challenge – In some cases, a healthcare provider may recommend a supervised food challenge. During this test, you consume a small amount of peanuts under close medical supervision so providers can monitor for allergic reactions and respond quickly if needed.

You may also be asked to keep a food diary, track allergic symptoms, or temporarily eliminate certain foods from your diet. Together, these diagnostic methods can help identify possible food allergies and guide the next steps in your care.

The most effective way to prevent an allergic reaction is to avoid peanuts and foods that may contain peanut ingredients or traces of peanuts.

When shopping for packaged foods, carefully review ingredient lists and allergen statements. Peanuts can sometimes appear in unexpected foods, including: [5]

• Baked goods
• Candy and chocolates
• Ice cream
• Sauces and marinades
• Energy bars
• Certain Asian and African dishes

Cross-contact can also happen in restaurants, bakeries, ice cream shops, and shared kitchens where peanuts are present.

If you or your child has a peanut allergy, it may help to communicate allergy information with schools, camps, caregivers, restaurants, and sports programs to reduce the risk of accidental exposure.

For individuals at risk of severe allergic reactions, a healthcare provider may recommend carrying epinephrine at all times in case of emergency.

While peanut allergies should always be evaluated and managed with a healthcare provider, understanding how your body responds to certain foods can still play an important role in your overall wellness. If you’re experiencing ongoing digestive discomfort or symptoms you suspect may be linked to certain foods, Everlywell’s Food Sensitivity Test can help you identify potential food sensitivities so you can make more informed choices about your diet.