A food allergy is an immune system reaction that occurs between two minutes and two hours after eating food. How to diagnose a food allergy? Most food-related allergic reactions actually relate to the proteins contained within certain foods which the immune system incorrectly identifies as harmful. Common allergens include peanuts, milk, tree nuts, eggs, shellfish and wheat.
A food allergy is different to a food intolerance. It is possible to prevent reactions to food intolerances. Symptoms of intolerance are often vague, but less serious than allergies and are often limited to digestive problems.
Symptoms of food allergies
Common symptoms of food allergies include:
- Hives or welts on skin
- Swelling of lips, eyes or face
- Abdominal pain.
Less visual symptoms of food allergies include:
- Difficulty breathing
- Swelling of the tongue
- Swelling or tightness in throat
- Difficulty talking or a hoarse voice
- Persistent cough.
Symptoms of anaphylaxis
In some people, a food allergy can cause a severe and possibly life-threatening reaction known as anaphylaxis. Symptoms of anaphylaxis include:
- Swelling of the lips, tongue or throat
- Shortness of breath, trouble breathing, wheezing
- Dizziness or fainting
- Stomach pain, vomiting, diarrhoea.
Many people at risk of anaphylaxis carry an epinephrine (adrenaline) autoinjector, commonly knon as an EpiPen. The device injects a single dose of medication when pressed against the thigh. In the case of an anaphylactic attack, the use of an autoinjector reduces the body’s allergic response. An autoinjector does not replace the need to go to hospital following an anaphylactic attack because the effects of epinephrine can wear off and cannot prevent a second reaction.
Doctors may recommend patients with allergies keep a food diary to identify mild allergens. A food diary lists all food eaten and medication taken, along with any symptoms experienced during the day. Food diaries can indicate which foods were consumed when symptoms occurred and help to narrow down or pinpoint suspected allergens.
Long-term restrictive diets should not be undertaken without medical supervision, as this can lead to malnutrition.
An allergy test can be undertaken if a patient needs further identifying what they’re allergic to. Allergy treatment will typically begin with a complete medical history, which will include questions on diet, family medical history and home and living area. This medical history assists the allergist in finding the cause of symptoms.
A skin test may be required to determine allergies. In a skin test for food, a small drop of a liquid food extract, one for each food tested, is placed on the skin. The skin is lightly pricked. If, after 20 minutes, a raised bump with redness appears, the patient is likely allergic to that food.
If the allergy is not pinpointed from the skin test, allergists may narrow the search by placing the patient on a special diet which typically removes common allergens. If symptoms decrease while on the diet and flare up again when the suspected foods are reintroduced, it is likely this food is the allergen.
Living with a food allergy
Strict avoidance of allergens is essential to managing symptoms. It’s important for people living with a food allergy to:
- Know the symptoms of allergic reactions and what to do if a reaction occurs
- Carry an autoinjector with them at all times
- Read and understand food labels
- Inform wait staff of allergies
- Be aware of cross contamination of foods.
We hope this has been informative on how to diagnose a food allergy. If you are experiencing symptoms of allergic reactions 13 DOCTOR recommends seeking medical advice on the best method of diagnosis. Book a telehealth consultation via phone or video conferencing here.