​The cause of food allergy is unknown. Children with a strong family history of food allergies are at higher risk of food allergy, suggesting that genes may contribute to developing food allergy. However, the exact genes that are responsible are unknown.

Environmental factors are also thought to play a part. Studies have shown that delayed introduction of foods into the baby's diet tend to increase the risk of developing food allergy. It is unclear how much this may hold true in an Asian population. This also means that the introduction of solid foods should not be delayed beyond 4 to 6 months of age, including the so-called "allergenic" foods like egg and peanut.

If your child consumes the food allergen, it can result in wheezing (an asthma attack), hives, allergic rhinitis (itchy nose, sneezing or blocked nose), vomiting and diarrhoea or stomach discomfort. The reaction tends to happen within 30 minutes after eating the offending food and can last up to 24 hours.

​Skin prick tests and blood tests can be done to help diagnose a food allergy. They are also used over time to track the likelihood of the child outgrowing that particular allergy.

Standard advice for food allergy is to avoid the foods. Immunotherapy, which reduces the risk of allergic reactions and improves quality of life, is available for certain food allergies such as peanut, cashew, pistachio, egg, milk and wheat. The child should preferably be 5 years old and above although exceptions do exist. If you are interested in this immunotherapy, please discuss it with our paediatrician specialising in allergy.

​If a reaction is clearly linked to the exposure to particular foods, you should consult a doctor. In the meantime, your child should avoid the suspected food. Even small amounts of it may cause a similar reaction.

It is good to keep a food diary if you are unsure whether the food causes your child's condition to worsen. It may help to indicate a hidden ingredient in the food that is causing the reaction. Bring the food diary with you when you consult the doctor.

Do not make the mistake of labelling your child with multiple food allergies without good evidence. Your child is growing and needs a variety of food to ensure adequate nutrition. Do consult a doctor for diagnosis.