Tree nut allergy most commonly affects infants and young children, although adults may also develop it. It is triggered by eating tree nuts or tree nut products such as oils and butters or using topical products containing tree nut oil. The allergy usually lasts for a lifetime, with fewer than 10% of individuals ever growing out of it.

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Tree Nut Allergy and Peanut Allergy Differences

A peanut allergy and tree nut allergy are often confused. Tree nuts such as cashews, hazelnuts, walnuts, pecans, almonds, Brazil nuts and pistachios are legumes like chickpeas and lentils, rather than nuts.

The proteins present in tree nuts are very different to those found in peanuts and someone who is allergic to peanuts will not necessarily be allergic to tree nuts. However, studies have shown that around 25% to 45% of people with a peanut allergy are also allergic to at least one type of tree nut.

Symptoms

The symptoms of an allergic reaction usually arise within 30 minutes of eating the tree nut and may include the following:

• Diarrhea
• Difficulty swallowing
• Abdominal cramps and pain
• Nausea and vomiting
• Runny nose
• Nasal congestion
• Itching in the mouth, eyes, throat or other area of the body
• Shortness of breath
• Anaphylaxis

A tree nut allergy is one of the allergies most often linked to a severe form of allergic reaction called anaphylaxis. This reaction can be life threatening, causing the airways to become blocked, blood pressure to fall and sending the body into shock. An allergist will recommend that people with a tree nut allergy carry an epinephrine autoinjector on them at all times, as this is the only treatment that reverses the symptoms of anaphylaxis.

Diagnosis

Since an allergy to tree nuts can cause anaphylaxis, it is essential that the allergy is accurately diagnosed. A doctor will ask about a person’s medical history, symptoms of previous allergic reactions and any family history of allergies. They may also arrange a skin prick test and/or blood test and if those tests fail to determine whether a person is allergic, an oral food challenge may be arranged. This involves giving the patient very small amounts of the food allergen and then increasing the amount over a period of time. Following each dose, the patient is assessed for any signs of reaction and if necessary, medication is prescribed.

Management

The best way to avoid triggering a reaction to tree nuts is to avoid exposure to them or any products that contain them. People who are diagnosed with an allergy to a certain tree nut may be able to tolerate exposure to other types of tree nut, but an allergist will usually recommend avoiding nuts altogether. Since tree nuts are among the most common foods to trigger allergy, they are listed in the 2004 Food Allergen Labeling and Consumer Protection Act, which stipulates that the nuts must be highlighted in the ingredients list of any food product. Tree nuts are commonly found in the following food items:

• Salad garnishes
• Asian cuisine
• Ice cream topping
• Sauces
• Desserts
• Baked goods
• Breads
• Baking mixes

Some alcoholic drinks also contain tree nuts or tree nut flavorings and tree nut oils may be present in lotions, hair products and soaps.