Tree Nut Allergy

What is Tree Nut Allergy?

Tree nut allergy is an immune system reaction to proteins found in tree nuts. When you eat tree nuts, your body mistakes the nut proteins for harmful invaders. Your immune system releases chemicals like histamine to fight off what it thinks is a threat. This reaction causes allergy symptoms that range from mild to life threatening.

Tree nuts include almonds, cashews, walnuts, hazelnuts, pecans, pistachios, macadamia nuts, and Brazil nuts. People with tree nut allergies may react to just one type of nut or to several different types. This allergy is different from a peanut allergy because peanuts are legumes, not tree nuts. However, many people with tree nut allergies also have peanut allergies.

Tree nut allergies usually develop in early childhood and tend to last a lifetime. Only about 9% of children with tree nut allergies outgrow them. This makes tree nut allergy one of the most persistent food allergies. The condition affects about 1% of the population in the United States.

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Symptoms

Tree nut allergy symptoms typically appear within minutes to two hours after eating nuts. Reactions can range from mild to severe. Common symptoms include:

Hives, itching, or eczema on the skin
Swelling of the lips, tongue, throat, or face
Tingling or itching in the mouth
Stomach pain, nausea, vomiting, or diarrhea
Runny or stuffy nose
Wheezing or difficulty breathing
Dizziness or lightheadedness
Anaphylaxis, a severe reaction that can be life threatening

Anaphylaxis requires immediate emergency treatment with epinephrine. Signs include trouble breathing, rapid pulse, drop in blood pressure, and loss of consciousness. Some people may have mild reactions initially and more severe reactions with later exposures.

Causes and risk factors

Tree nut allergy develops when your immune system incorrectly identifies nut proteins as dangerous. Your body creates immunoglobulin E antibodies, or IgE antibodies, against the nut proteins. When you eat that nut again, the IgE antibodies recognize the protein and signal your immune system to release histamine and other chemicals. These chemicals cause allergy symptoms throughout your body.

Scientists do not fully understand why some people develop food allergies and others do not. Risk factors include having other allergies like eczema or asthma, having a family history of allergies, and being a child. Early introduction of tree nuts in infancy may reduce allergy risk in some cases. However, if you already have a tree nut allergy, avoiding nuts completely is the only way to prevent reactions.

How it's diagnosed

Doctors diagnose tree nut allergies through your medical history, physical exam, and specific allergy tests. Your doctor will ask about your symptoms, what you ate, and how quickly symptoms appeared. They may recommend a skin prick test, where tiny amounts of nut proteins are placed on your skin to check for reactions. Blood tests can measure IgE antibody levels for specific tree nuts like almonds, cashews, walnuts, and hazelnuts.

A food challenge test may be necessary if other tests are unclear. During this supervised test, you eat small amounts of the suspected nut while doctors monitor you for reactions. Talk to a doctor about specialized allergy testing to identify which tree nuts trigger your symptoms. Getting accurate diagnosis helps you avoid the right foods and carry proper emergency medications.

Treatment options

Treatment for tree nut allergy focuses on avoiding nuts and managing reactions when they occur. Key approaches include:

Strict avoidance of all tree nuts or specific nuts you are allergic to
Reading all food labels carefully for nut ingredients and cross contamination warnings
Carrying epinephrine auto injectors at all times for emergency treatment
Wearing medical alert jewelry that identifies your allergy
Creating an action plan with your doctor for treating reactions
Antihistamines for mild symptoms like hives or itching
Education about hidden sources of nuts in foods and personal care products
Working with a dietitian to maintain balanced nutrition while avoiding nuts

If you experience signs of anaphylaxis, use your epinephrine auto injector immediately and call 911. Never wait to see if symptoms improve on their own. Some people experience a second wave of symptoms hours after the first reaction. Always seek emergency care after using epinephrine, even if you feel better.

Frequently asked questions

Yes, tree nut allergies can develop at any age, even if you have eaten nuts without problems for years. Adult onset food allergies are becoming more common. If you notice new symptoms after eating nuts, stop eating them and see a doctor for allergy testing. Adult tree nut allergies rarely go away on their own.

Not necessarily, but many people with tree nut allergies react to multiple types of nuts. Studies show that about 30% to 50% of people with tree nut allergies are allergic to more than one type. Your doctor may recommend avoiding all tree nuts to be safe, or they may test you for each type individually. Cross contamination during food processing also makes it risky to eat any tree nuts.

Peanuts are legumes that grow underground, while tree nuts grow on trees. These are botanically different foods that cause separate allergies. However, about 25% to 40% of people with peanut allergies also have tree nut allergies. Many people avoid both types of nuts because they are often processed in the same facilities, creating cross contamination risk.

Tree nuts hide in many unexpected foods including pesto, marzipan, nougat, pralines, gianduja, satay sauce, and mortadella. Baked goods, cereals, granola bars, salad dressings, and ice cream may contain nuts or nut oils. Some barbecue sauces and marinades use nut butter for thickness. Always read ingredient labels carefully and ask about ingredients when eating out.

Highly refined nut oils generally do not contain enough protein to trigger allergic reactions. However, cold pressed, expelled, or extruded nut oils may contain nut proteins and should be avoided. Many doctors recommend avoiding all nut oils to be completely safe. Check with your allergist before using any products containing nut oils.

Blood tests that measure IgE antibodies to specific tree nuts are helpful diagnostic tools. Higher IgE levels generally indicate a greater likelihood of allergy, but test results must be interpreted alongside your symptoms. Some people with positive blood tests can tolerate small amounts of nuts, while others with lower levels have severe reactions. Your doctor will use blood tests combined with your medical history to make a diagnosis.

Most people with tree nut allergies only react when they eat nuts. Skin contact might cause local hives or irritation but rarely causes severe reactions. Smelling nuts is unlikely to cause anaphylaxis because nut proteins are not airborne in normal situations. However, inhaling nut particles from grinding or crushing nuts in enclosed spaces could trigger respiratory symptoms in some people.

If you have mild symptoms like itching or hives, take an antihistamine and monitor yourself closely. If you have any signs of a serious reaction like trouble breathing, throat tightness, or dizziness, use your epinephrine auto injector immediately and call 911. Never delay using epinephrine hoping symptoms will improve. Always seek medical evaluation after any reaction.

There is currently no cure for tree nut allergy. Oral immunotherapy, where you consume tiny increasing amounts of the allergen under medical supervision, is being studied for tree nuts. This treatment may increase tolerance in some people but does not cure the allergy. The treatment is not yet widely available and carries risks of serious reactions during the process.

Current guidelines suggest introducing common allergens including tree nuts early in infancy, around 4 to 6 months of age. Early introduction may reduce allergy risk in some children. Use nut butters thinned with water or breast milk rather than whole nuts to prevent choking. If your child already shows signs of food allergies or severe eczema, talk to a doctor before introducing nuts.