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Food allergies and how to spot them

Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 4 minutes read

Food allergies are on the rise and can cause a great deal of alarm, particularly to parents. How do you know if you or your child has an allergy? Let's take you through the most common food allergies and how you can spot the signs.

An allergy to a particular component in food prompts the immune system to go into overdrive, giving symptoms in the gut, skin and airways. Food allergies are common in young children, but most grow out of these as their immune system develops.

Reactions vary from mild to severe. They may be as common as affecting one in 10 adults, and up to half of these were reported to have had a severe reaction, according to one study.

Doctor’s advice

Which allergies do children get?

The most common childhood allergies are to eggs, milk and peanuts. Others include wheat, soy and tree nuts (almonds, hazelnuts, cashews and pistachios). Peanuts, tree nuts, fish and shellfish tend to cause the most severe reactions.

Many children grow out of food allergies by the age of five. It’s not known why food allergies develop, but you’re more likely to have a food allergy if you also have hay fever, asthma and eczema, or if anyone in your family has these. With eczema, the earlier it appears and the worse it is, the more likely a food allergy will emerge.

Which ones persist to adulthood?

Shellfish tops the list of food allergies in adults. Childhood allergies more likely to persist include peanuts, tree nuts, fish and shellfish. Some fresh fruits can also cause a reaction. If you have a true allergy, you only need a small amount to provoke a response, and reactions can get worse with repeated exposure.

What should I look out for?

The most accurate way to work out if you or your child has an allergy is to keep a food diary. List the foods you’ve eaten, any symptoms, and how long after eating the symptoms came on. This will help you spot any patterns and pinpoint potential allergies.

Gut symptoms may give you stomach pain, nausea, vomiting and diarrhoea. You may notice a red raised itchy rash, known as hives (urticaria), or your eczema may get worse. You may get itching or tingling around your mouth and throat, and perhaps mild lip or tongue swelling. This happens particularly in allergy to certain fresh fruit and vegetables and is avoided by thoroughly cooking them.

Mouth and throat symptoms carry a risk of the airways swelling and causing breathing problems. This is potentially life-threatening and can lead to a condition called anaphylaxis, where you are unable to breathe. This is a medical emergency and requires immediate medical attention.

Any food allergy symptoms can come on within seconds or minutes of eating – this is usually an IgE-mediated (immunoglobulin E) allergy. This carries the risk of breathing problems and anaphylaxis. Alternatively, a non-IgE-mediated food allergy may take several hours to come on, so is harder to pair with a particular food. It’s caused by other parts of the immune system.

A food intolerance is not an immune reaction so it's not a true allergy, it’s a difficulty digesting a particular food. Gut symptoms may be similar to allergy, but with more bloating and excess wind. The most common food intolerances are to lactose and casein, both found in milk, and to gluten in wheat and some grains. Gluten intolerance is separate from coeliac disease and wheat allergy.

When should I see my doctor?

The best way to prevent an allergic reaction is to avoid the offending food, so it’s important to identify it. If you have suspicions for yourself or your child, book an appointment with your doctor, who will listen to your concerns, look at any related medical conditions, and they may refer you or your child to an allergy service. Take your food diary to any appointments, as this will help with assessing you, and they may consider allergy tests.

If your asthma has flared up and you think this may be related to a particular food, again, book with your doctor to discuss the next step in treatment or referral.

Although rare, food allergies can be life-threatening if anaphylaxis occurs. It is not common but it is life-threatening and can develop quickly. It causes swelling of the airways and difficulty breathing, along with feeling faint, dizzy, sick and you may collapse. Someone should call 999 immediately with any of these symptoms.

If you’ve had an anaphylactic reaction, you may be kitted out with an EpiPen, which you will carry at all times. This contains adrenaline and you will be taught to administer it in the event of an emergency. It’s a good idea to wear a medical bracelet, too, to alert everyone in the event of an emergency.

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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