Food allergies are a common problem, especially in children.
Common foods that can trigger allergies include nuts, milk, eggs, and shellfish. Some allergies in children (such as milk and eggs) tend to be outgrown with age, while others (such as nuts and shellfish) tend to persist into adulthood.
An allergen is something that triggers an allergic reaction. Currently, the only “treatment” for food allergies is strict avoidance of anything containing the allergen. In the case of accidental ingestion, medications can be used to treat allergy symptoms, which can range from mild to severe. Mild symptoms include rash (hives), itching, and swelling of the lips and tongue. More severe symptoms can include trouble breathing, wheezing, throat swelling, and nausea, vomiting, or diarrhea. A very severe allergic reaction is called anaphylaxis, which can be life threatening and requires immediate medical attention.
It is important not to confuse a food allergy with food intolerance. A true food allergy results from an overactive immune system targeting an allergen found in food. Food intolerance, in contrast, is when a person has trouble digesting certain foods. This intolerance can come from a number of factors related to the gastrointestinal tract and the body, but it does not involve the immune system. Symptoms of food intolerance can include bloating, gas, abdominal pain, and diarrhea. An example is lactose intolerance.
Immunotherapy uses a tiny amount of an allergen to trigger a mild immune response in the body without causing a full allergic reaction. Repeating these exposures over time (several years) allows the body to become used to the allergen and eventually produce less of an allergic reaction. This process is called desensitization. Immunotherapy can be delivered to the body as an injection under the skin (subcutaneous immunotherapy, commonly known as allergy shots) or as a pill that is swallowed (oral immunotherapy) or placed under the tongue (sublingual immunotherapy).
Allergy injections are currently used to treat seasonal and environmental allergies as well as allergies to insect stings. However, they are not used to treat food allergies because earlier studies showed too high of a risk of severe side effects such as anaphylaxis.
Although immunotherapy is currently not standard treatment for food allergies, it is an area of active research. Studies are currently being done on several types of immunotherapy for food allergies.
Oral immunotherapy has been shown fairly effective at producing desensitization; however, the risk of severe side effects is high.
Sublingual immunotherapy may be safer than oral immunotherapy in terms of severe side effects; however, the treatment effect seems to wear off more quickly after treatment is stopped.
Epicutaneous immunotherapy: Recent studies have been done using a skin patch to deliver allergens into the body instead of an injection under the skin (epicutaneous as opposed to subcutaneous). This technique appears safer than the injection in terms of risk of severe side effects, but longer-term data are needed on effectiveness. The November 21, 2017, issue of JAMA contains an article discussing an early trial using epicutaneous immunotherapy to treat peanut allergy in children.
Different types of subcutaneous immunotherapy: Even though studies using traditional allergy injections for food allergies showed too much risk, newer types of subcutaneous immunotherapy, such as using smaller fragments of allergens, are being studied.
Asthma and Allergy Foundation of Americawww.kidswithfoodallergies.org/
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Sources: Sampson HA, Shreffler WG, Yang WH, et al. Effect of varying doses of epicutaneous immunotherapy vs placebo on reaction to peanut protein exposure among patients with peanut sensitivity: a randomized clinical trial. JAMA. doi:10.1001/jama.2017.16591
Jones SM, Burks AW. Food allergy. N Engl J Med. 2017;377(12):1168-1176.
Topic: Allergy and Immunology
Jill Jin. Treatments for Food Allergies. JAMA. 2017;318(19):1945. doi:10.1001/jama.2017.17306