In 1991, Dr. Sobel, DDF founder, was among the first to pioneer the union of cosmetic dermatology and topical skin care when he founded HDS Cosmetic Lab, a line of skin-care products that delivered excellent results without a prescription. The line quickly became popular and was available through upscale spas, estheticians, and small retail stores. In 1995, the company was born and named DDF (Doctor's Dermatologic Formula) to help define the brand as a doctor's dermatologic line. DDF developed its legendary mantra — Cleanse. Protect. Treat. — focusing on anti-aging (preventative and restorative), acne, hyperpigmentation, rosacea, sun protection, and sensitive-allergic conditions. DDF expanded distribution to spas, retail stores, and international markets, becoming one of the first doctor-preferred skin-care lines sold at Sephora when the chain debuted in the U.S. in 1998.