Food allergies are on the rise, with an estimated 2 million people in the UK with a diganosed food allergy. Hospital admissions for allergic reactions are increasing sharply over time. Food allergies can cause unpleasant symptoms such as hives, diarrhoea, vomiting and in severe cases, anaphylaxis. The most important way to manage food allergies is strict avoidance of the foods that cause a reaction. So why are we told it is important to get medical advice and support if a food allergy is suspected? Can't we just self diagnose food allergies?
WHAT IS A FOOD ALLERGY?
A food allergy is an adverse immune system reaction to a food substance that is normally considered harmless, for example nuts, peanuts, milk or eggs. Note that a food allergy is not the same as a food intolerance. A food intolerance may cause similar symptoms to a mild allergic reaction, but is due to an inability to digest the food. It usually only causes digestive distress, and doesn't involve the immune system.
There are two main types of food allergy: IgE mediated and non-IgE mediated. Let's take a closer look at each of these:
IGE MEDIATED FOOD ALLERGY
An IgE-mediated food allergy is an immediate reaction to the food in question. This means symptoms start to appear within minutes or up to two hours of eating the food. These types of reaction can affect multiple organs within the body and you might see symptoms such as:
swelling or itching in the face or throat
hives (an itchy, red, raised rash on the skin)
A severe allergic reaction, anaphylaxis, can be life threatening. If you suspect someone is experiencing anaphylaxis you should use their adrenaline auto-injector (if they have one) and call an ambulance immediately. Symptoms of anaphylaxis include:
feeling dizzy or faint
confusion or anxiety
collapsing or losing consciousness.
NON-IGE MEDIATED FOOD ALLERGY
A non-IgE mediated food allergy involves delayed reactions to a food or foods. These reactions tend to appear after two hours and within three days of eating a food. Symptoms might include:
Reflux and/or heartburn
Diarrhoea and/or constipation
Skin rash or eczema
Blood and/or mucus in stools
In severe cases, non-IgE mediated food allergies in children can cause shock, dehydration, refusal to feed, and failure to thrive.
HOW ARE FOOD ALLERGIES DIAGNOSED?
There are two main methods for diagnosing food allergies. The first is allergy testing, and the second is by completing an exclusion diet. Let's take a look at these two options in more detail.