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In people with food allergies, the immune system becomes sensitized to the protein of a particular food or foods. Whenever you eat an allergenic food, your immune system mounts an attack against it that involves the release of inflammatory chemicals. These chemicals cause food allergy symptoms. Symptoms usually arise within two hours of eating an allergenic food.
Symptoms of food allergies vary widely in each individual and can change over time. Reactions may affect the body in different ways at different times. Reactions may be mild one day and life-threatening the next.
Since people with food allergies are also more likely to have non-food allergies, asthma, eczema, and atopic dermatitis, it may be difficult to tell the precise cause of an allergic reaction.
Medications may help treat some symptoms of food allergy.
Types of food allergy symptoms
Food allergy symptoms can impact many different systems in the body. The most common food allergy symptoms occur in the skin, respiratory system, gastrointestinal (digestive) system, and in the nervous system. The most dangerous potential symptom of food allergies is anaphylaxis.
Anaphylaxis is a potentially fatal allergic reaction. Anaphylaxis involves hives and swelling, which can tighten the throat and block breathing. Nausea, vomiting, abdominal pain, and diarrhea may occur. The blood pressure drops, which may result in dizziness and fainting. The pulse becomes weak and rapid. Some people feel a sense of impending doom. Anaphylaxis can cause shock – inadequate blood flow that deprives tissues of oxygen – or heart attack.
If anaphylaxis is not immediately treated with Epinephrine, it can be fatal. As long as 12 hours after an anaphylactic reaction, some people have a second reaction known as a biphasic reaction. For this reason, the administration of Epinephrine must always be followed up by emergency medical treatment.
The eight major food allergens – eggs, fish, milk, peanuts, shellfish, soybeans, tree nuts, and wheat – are the foods most likely to cause anaphylaxis, but any food can cause anaphylaxis. Exercising soon after eating an allergenic food may raise the risk for an anaphylactic reaction.
Those who have had one anaphylactic reaction are at risk of having another.
Skin symptoms of food allergies
Food allergies cause skin symptoms for many allergic people. A large number of people with food allergies also have other allergies and skin conditions that may contribute to dermatological symptoms. Skin symptoms of food allergies may include:
Respiratory symptoms of food allergies
Since food particles can be inhaled during preparing or eating, respiratory symptoms of food allergies are very common. Food allergy symptoms that involve the lungs, sinuses, and respiratory tract include:
Gastrointestinal symptoms of food allergies
Since food enters the mouth and travels through the gastrointestinal system, it makes sense that the digestive tract is often the scene of intense allergic reactions in those with food allergies. Gastrointestinal symptoms of food allergies can include:
Cardiovascular symptoms of food allergies
Food allergies can cause dysfunctions in the heart and blood vessels, especially during severe allergic reactions. Chemicals released by the immune system can cause the blood vessels to dilate (widen), which may result in:
General symptoms of food allergies
In some people, food allergies cause neurological or psychological symptoms such as mood swings, depression, anxiety, and a feeling of impending doom. Children with food allergies may display worsened behavior after eating allergenic foods.
In others, food allergies can cause headaches, itching and watering eyes, or uterine contractions.
What symptoms lead to a diagnosis of food allergies?
Food allergies cannot be diagnosed based on symptoms alone. The process of diagnosing food allergies has several steps. The allergist assesses symptoms during a physical exam and considers risk factors based on personal and family medical history. A skin or blood test helps narrow down potentially allergenic foods. Possible allergens are further confirmed by an elimination diet and sometimes a food challenge.
At what age do most people first experience food allergy symptoms?
Food allergies are most common in babies and young children. Rarely, adults can develop food allergies. Early symptoms often include swelling, tingling, or itching in the mouth, or skin symptoms such as hives or eczema.