Menarini Tretinoin Gel (20g) USP is a form of vitamin A. When applied on scalp, it works by promoting the growth of hair follicles, thereby stimulating hair growth. When used on skin, it reduces oil production in the skin, replenishes acne-prone skin and helps keep your pores open. It is a medicine which is a form of Vitamin A that is used to treat acne, which appears as spots or pimples on your face, chest or back. It also helps to smooth rough facial skin and to reduce the appearance of fine wrinkles in the skin. used to treat acne, which appears as spots or pimples on your face, chest or back.