What is a food allergy?
A food allergy is a condition in which the immune system reacts toward certain types of food. Symptoms often occur within minutes or hours after eating the food. The allergic reaction may cause itchiness, swelling of the tongue, vomiting, diarrhea and difficulty breathing. The most common causes of food allergies are eggs, fish, milk, peanuts and soy. Food allergies are most common in babies and children. Developing an allergy to a type of food which had been previously eaten is possible, though uncommon. Some people will grow out of their allergy as they age, especially allergies to eggs, soy and milk.
Many people have food intolerance (such as lactose intolerance, celiac disease, etc), instead of true food allergy. Food allergy occurs when the immune system overreacts to a normally harmless substance. These substances are called allergens or triggers. Common causes of food allergy include eggs, milk, peanuts, soy, fish, shellfish, tree nuts (Brazil nuts, macadamia nuts, etc.) and wheat, among others. Food allergy symptoms are most commonly diagnosed in babies and children, but they can also develop later in life. People with other allergic conditions, or who have family members with allergic conditions, such as hay fever and eczema, often also have food allergies.
The symptoms of an allergic reaction usually begin within 2 hours after eating. They may involve the skin, the gastrointestinal tract, the cardiovascular system and the respiratory tract. The symptoms include hives, hoarse voice, rashes, itching and swelling (of the mouth, lips, tongue, throat and eyes), difficulty swallowing, congested nose, shortness of breathing, abdominal pain, nausea/vomiting and even cardiovascular collapse.
Diagnosis is usually made based on the symptoms and excluding the suspected cause from the diet, to see if symptoms improve. If the cause is unknown, or excluding the food doesn't clearly improve symptoms, other tests for allergy, such as skin prick tests and blood tests, may be helpful in diagnosing the trigger.
Food allergies are generally treated by identifying and avoiding the triggering food. People with a mild reaction may find that antihistamine medications help to relieve itching. Severe allergic reactions require emergency treatment. These people may be prescribed an EpiPen/Jext which is used to deliver adrenaline in an emergency.
Getting a definite diagnosis of triggers may help to avoid these and reduce or completely stop symptoms. For some people, it is possible to undergo desensitization therapy, which means the body is slowly exposed to the trigger responsible for their allergy. This causes the immune system to slowly get used to the trigger, helping to reduce the severity of the allergic reaction in the future.