These days an increasing number of people are developing allergies in many different forms, such as skin rashes, breathing difficulties, and tiredness. This guide offers three approaches to the problem: first, allergic symptoms are listed and cross-referenced to known allergens and suitable tests to discover which really is the cause; second, there are separate sections for specific allergies; and third, there is an A-Z of allergens which gives advice on testing to find out whether you have allergies to that substance.