Persistent rashes can be caused by a contact allergic dermatitis to chemicals and everyday ingredients with which the skin has regular exposure. This can include personal hygiene products, clothing and occupation-related materials. Allergy patch testing at SkinSafe Dermatology in Beverly Hills involves the application of individual, standardized allergens to the upper back, which are left in place for 48 hours. After a subsequent 24 hours, the back is re-evaluated. Reaction to a particular allergen may suggest the cause for the rash. Dr Shainhouse will provide counselling on the relevance of the positive findings and how to avoid this chemical in the future.