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The two are often believed to be interchangeable, but the main difference is that retinol is eventually converted into retinoic acid. Retinol is a natural form of vitamin A, while Retin-A is derived from retinoic acid, a synthetic derivative of vitamin A, and considered pharmaceutical.
Get a prescription for Retin-A. Retin-A is the brand name version of the generic drug known as tretinoin. It is available only with a doctor's prescription, so you will need to make an appointment with a dermatologist if you are interested in trying this treatment.