Symptoms of food allergies and intolerances
A food allergy is a response by the body’s immune system to a particular food. The immune system responds to the food as if it were toxic. Food allergies can occur immediately (‘immediate onset’) or after some time has passed (‘delayed onset’).
A food intolerance is a reaction in your body, caused by a substance in the food you’re eating. It is not caused by your immune system responding to the food. It often has a delayed onset.
||Between a few minutes to three hours after exposure
- Skin reactions (such as redness, hives or dermatitis)
- Itchy mouth or eyes
- Vomiting, stomach pain, diarrhoea
- Nasal congestion
- Swollen face (angioedema), including swelling of eyelids, face, lips, tongue. This can constrict airways and make it hard to breathe
- Anaphylaxis, or anaphylactic shock. This is a severe and life-threatening reaction. A person might have a persistent cough, wheezing, hoarse voice, shortness of breath and difficulty swallowing. The person might even pass out (suggesting a drop in blood pressure).
||Up to two days after exposure
- Gastrointestinal symptoms such as vomiting, diarrhoea and stomach cramps
||Up to two days after exposure
- Constipation, diarrhoea, stomach pain
- Skin redness and dermatitis
What to do about food allergies
There is no cure for food allergies. Many children grow out of them, though. You can also take some steps to make it easier for you and your child to live with allergies.
Avoid the food
It is important to avoid the food. This can be challenging, particularly if eating even tiny amounts causes a reaction. It’s also necessary to avoid any foods or cutlery that could have been in contact with the food your child’s allergic to.
You can do two important things to help your child avoid the food.
Read labels on all foods. Be aware that some allergenic foods have different names, such as ‘whey’ or ‘casein’ for cow’s milk protein. By law, the 10 most common allergens need to be stated on food labels.
Be careful when you eat out. Eating out can be quite difficult. You should be prepared to find out what ingredients each dish includes, how it was prepared, whether it has touched any other foods, and whether there is any risk of cross-contamination. Most restaurants are happy to help you with this information, but they might be unsure about the ingredients of some of their foods, such as sauces. Buffets and bain maries (food warmers) are best avoided because there is a good chance ingredients have been moved from one dish to another.
Have an emergency plan
You should talk to your doctor about an emergency plan. This will help you recognise and treat symptoms if your child eats something that causes an allergic reaction.
- Your doctor might suggest your child wears a medical bracelet that explains the allergy.
- If the allergy carries a risk of anaphylaxis, you might be prescribed a device called an EpiPen, which makes it easy to self-inject adrenaline. Your doctor will teach you and your child (if old enough) how to use this EpiPen.
- It’s important that key people – such as family, carers, babysitters and your child’s school – know about your child’s EpiPen and how to use it correctly.
What to do about food intolerances
Symptoms of food intolerance are usually less severe than those of allergies.
If a doctor has diagnosed food intolerance in your child and your child eats something you know she’s intolerant of, she shouldn’t need medical attention. The symptoms will usually clear up by themselves. If your child’s symptoms include diarrhoea, you need to ensure she gets plenty of water.
If you’re not sure why your child is having a reaction, and there is a possibility the reaction could be due to a food allergy, it’s best to consult your doctor.
Diagnosing food allergies and intolerances
If you think your child has a food allergy or intolerance, the best place to start is with a visit to your doctor. Your doctor might refer you to an allergist, who might consider performing further tests.
Tests for immediate-onset allergies include the following:
Skin-prick test (SPT): the allergist will put a small amount of the possible allergy-causing substance on your child’s skin. Then the allergist will prick your child’s skin with a small toothpick-like device. A red lump might come up where the skin has been pricked. Your child’s allergist will talk you through the results of this test.
Blood tests: the RAST (radio allegro sorbent test) might be used to see whether a substance called IgE is in your child’s blood. Blood will usually be taken from your child’s arm, and sent away for testing.
Elimination diet: this involves removing possible allergy-causing foods from your child’s diet, then reintroducing them again if the allergist thinks it’s safe to do so. Your allergist is looking to see whether your child’s symptoms flare up when the foods are put back into the diet.
Oral food challenge: your child will be given the possible allergy-causing food to eat in a safe, supervised setting. Medical and nursing staff will watch to see whether an allergic reaction occurs. This test carries a risk of causing a severe allergic reaction and should be conducted only by a specialist in a supervised setting.
If your child has a delayed-onset allergy, testing is more difficult. The most commonly used test is an elimination diet (see above).
A new test, called the food patch test, is being trialled. This involves putting a patch with an extract of the possible allergen on your child’s skin to see whether dermatitis develops.
Elimination diets are also the most common test for food intolerances. For suspected fructose or lactose intolerance, a breath test can also be used. This tests the amount of hydrogen gas in the child’s breath. Lactose-intolerant children will have higher levels of hydrogen in their breath.