Tretinoin (TT)

Tretinoin is the carboxylic acid form of vitamin A. It is a first generation topical retinoid commonly used to treat acne vulgaris and keratosis pilaris. Tretinoin is most commonly used as a form of acne treatment. It was the first retinoid developed for this type of topical use.[citation needed] Tretinoin is the best studied retinoid in the treatment of photoaging. It is used by some as a hair loss treatment and is a component of many commercial products that are advertised as being able to slow skin aging or remove wrinkles. Topical tretinoin is also used to treat and reduce the appearance of stretch marks by increasing collagen production in the dermis. It is a teratogen, and therefore can cause birth defects and tests have shown increases in fetal skull abnormalities in rats. Women who are or may be pregnant, or who are seeking to become pregnant, are therefore warned against using it.