Self-diagnosis of food allergy is notoriously unreliable, and failing to have a serious food allergy diagnosed could be potentially life threatening. Therefore, if you suspect that you have a food allergy you should seek specialist medical advice.
To diagnose food allergy the medical specialist will usually first talk with you about your symptoms, examine you for symptoms, and test if your immune system has created food-specific IgE antibodies. Skin prick testing and blood tests are the main tests used for this purpose. However, the presence of specific IgE does not necessarily mean that you will experience symptoms. Therefore, sometimes the only way to accurately diagnose a food allergy is to remove the suspected food from the diet to see if symptoms improve and if they do, give the suspect food in gradually increasing amounts to see if symptoms reappear. This is called a food challenge. Allergy specialists will always supervise the performance of challenge tests in a hospital or clinic, where the staff has established routines to safely manage any serious reactions.