letter no. 1
Do I really need a patch test before at-home hair colour?
the desk replies — For a new vendor or a new product line, yes, 48 hours before, on the inner arm or behind the ear. PPD allergy can develop after years of trouble-free colouring, and reactions range from an itchy scalp to swelling that needs urgent care. A professional who waves the test away on a first visit is cutting a corner you can see.