For many cosmetic and beauty products, medical approval is so highly rated that it appears with big letters in advertising and on the packaging itself. “Dermatologist approved,” “gynaecologically tested,” and “dermatologically tested” are stamped on retail products from shower gels to baby cream and even things like lipstick. But what do these indicate, and what does “testing” or “approval” actually mean?

Persil says that its non-biological liquid detergent, for example, is “the ideal choice for new-borns . . . it’s dermatologically tested with research recognised by the British Skin Foundation.”1 Femfresh Daily Intimate Wash is advertised as being “gynaecologically tested unlike regular soaps and shower gels.”2 Aveda, which is owned by Estée Lauder, offers products for children that are “paediatrician-tested, safe and effective for people aged six months and older. They are allergy- and dermatologist-tested.”3

I contacted six companies that use these types of claim to promote their products, asking them …