Many substances can cause allergies. Common ones are: foods, medicines, insect stings, dust and pollen.
Foods
Any food can cause an allergy. Some are more common than others. It also depends on where you live. For instance allergy to olive tree pollen is common in Mediterranean countries. Bird's nest soup allergy is common in Singapore.
Common food allergies in the UK are: Cow's milk, Egg, Peanut, Tree nuts, Fish, Shellfish, Sesame and Soya.
You can even get allergies to fruit and vegetables such as apples, melons and pears but these usually just cause an itchy mouth (oral allergy syndrome) and occur in older children with hay fever.
Dust, pollens and animal dander
Dust, grass and tree pollen and furry and feathered animals can make you sneeze and sometime also trigger asthma and eczema. Most of the time these allergies are mild. If it is troublesome and affecting your child's sleep and activities at home and at school see your doctor. Sometimes we can make you less allergic using desensitisation therapy.
Medicines
Any medicine or vaccine can cause an allergy. These are uncommon in children. 90% of children who think they have an allergy to medicines don't. Get it checked out. It may not be a problem.
Jewellery and make-up
Particularly in teenagers, make-up, nickel jewellery, soaps and after-shave can sometimes irritate the skin. It is usually pretty obvious what is causing the problem and the treatment is simple - avoid. Most of the time no allergy tests are needed. Sometimes if it is very troublesome allergy patch tests are useful but these are quite complicated to perform and only available in a few dermatology centres in the North West.