What to Know About a Walnut Allergy

Walnuts are a popular and nutritious addition to salads, frozen desserts, and baked goods. But for some people, they can cause an allergic reaction. In the case of a severe walnut allergy, the reaction can life-threatening.

If you or your child has a walnut allergy, understanding the symptoms and how to manage them is crucial.

An allergy is an immune system response to a substance the body mistakenly identifies as harmful. In the case of a walnut allergy, your immune system reacts to proteins found in walnuts or walnut oil. When you eat, touch, or — for certain people — even inhale walnut particles, your body releases chemicals, including histamine, which causes a range of symptoms.

Walnuts are a type of tree nut. According to the American Academy of Allergy, Asthma & Immunology (AAAAI), an allergy to tree nuts is one of the nine most common food allergies, affecting roughly 0.5 to 1 percent of the U.S. population. People with a walnut allergy may also be allergic to other tree nuts, such as pecans, cashews, almonds, hazelnuts, and pistachios. However, not everyone with a walnut allergy is allergic to all tree nuts. (Also, while you can be allergic to both peanuts and tree nuts, peanuts are not technically nuts, but legumes.)

Your doctor can help you determine which nuts you need to avoid through allergy testing.

Most tree nut allergies start in childhood. Around 10 percent of people will eventually outgrow them, per the AAAAI.

Symptoms of an allergic reaction can appear within minutes to a few hours after exposure to walnuts and can vary from mild to severe. According to Cleveland Clinic, symptoms may include the following:

• Hives, redness, swelling, or a rash
• Itching or tingling in the mouth; swelling of the lips, tongue, or throat
• Nausea, stomach cramps, vomiting, or diarrhea
• Sneezing, runny nose, nasal congestion, or asthma-like symptoms

Anaphylaxis

Anaphylaxis is a severe, life-threatening reaction to an allergen. Anaphylaxis is a medical emergency and requires immediate treatment with epinephrine (like an EpiPen) and a call to 911.

According to Cleveland Clinic, signs of anaphylaxis include the following:

• Shortness of breath
• Swelling of the lips, mouth, and tongue
• Difficulty swallowing
• Lightheadedness or fainting

People with known walnut allergies should always carry injectable epinephrine, available with a doctor's prescription. A medical bracelet can also be a lifesaver.

The only way to prevent an allergic reaction is to completely avoid walnuts and products containing them.

• Read ingredient labels carefully. Walnuts can be found in many foods, including baked goods, candy, granola, cereals, and sauces. The U.S. Food and Drug Administration requires manufacturers to list common allergens like tree nuts. Look for "walnut" or "tree nut" on the label.
• Be aware of cross-contamination. Cross-contamination occurs when a food that does not contain walnuts is prepared with the same utensils or on the same surfaces as a walnut-containing product, according to Food Allergy Research and Education. Many food labels say if a product was made in a facility with tree nuts, even if it doesn’t contain them. If you're dining out, inform your server about the allergy and ask about preparation methods.
• Inform others. Make sure that your family, friends, and school staff are aware of the allergy.
• Carry an epinephrine auto-injector. If you have been diagnosed with a severe walnut allergy, your doctor will likely prescribe an epinephrine auto-injector (EpiPen, Auvi-Q, Neffy). Always carry it with you and make sure that you know how to use it.