A cashew allergy can be a mild to severe reaction that occurs shortly after ingesting any quantity of the nut. It is one of the less common food allergies, and many people with the problem also experience adverse reactions to related tree nuts, such as pistachios and walnuts. During an allergic reaction, a person may have throat and tongue swelling, breathing difficulties, chest tightness, and skin hives. Rarely, a cashew allergy can be severe enough to induce anaphylaxis, a full-body reaction that can become life-threatening without immediate treatment. Most people can control their allergies by avoiding foods containing cashews and using over-the-counter antihistamines in the case of accidental ingestion.
Allergies are caused by unusual immune system responses to specific food items, pollens, chemicals, or other normally harmless substances. In the case of a cashew allergy, the immune system mistakes the nut as a threat and releases an antibody called immunoglobulin E (IgE) to combat it. IgE antibodies then induce inflammation in the mouth, throat, gastrointestinal tract, or skin. Specialized cells called mast cells found throughout the body respond in turn by releasing additional inflammatory chemicals. Some people who have cashew allergies first experience reactions in early childhood, and for reasons not entirely understood by doctors, outgrow the problem by their adult years.
An individual with a cashew allergy can develop a variety of symptoms within the first two hours of ingestion. Signs of an allergic reaction can include itchy skin hives, wheezing, hoarseness, and a feeling of tightness in the chest and throat. A moderate to severe cashew allergy can induce swelling in the lips, tongue, and throat that make breathing and talking difficult. If the intestines are involved, a person might experience diarrhea, stomach pain, and vomiting. Anaphylaxis can cause airways to become completely blocked and cause a dangerous drop in blood pressure.
An immunologist can diagnose a cashew allergy and identify other offending foods with blood and skin-prick tests. If allergies are limited to only a few foods, the doctor may simply advise the patient to avoid them. Over-the-counter medications are usually enough to combat symptoms of minor reactions. Regular allergy shots might be a good idea for people who are allergic to several different foods and other substances to prevent frequent attacks.
Anaphylaxis is an emergency situation that requires immediate medical care. A patient is treated in the emergency room with an injection of epinephrine, a chemical that immediately stops the immune system's attack on the body. Following hospital care, patients who are at risk of future anaphylactic reactions are usually given epinephrine syringes to keep nearby at all times in the event of a future attack.