Tretinoin is used to treat severe acne, acne scars, sun damage, and hyperpigmentation. It comes in three levels of strength i.e 2.5, 5, and 10%. Always start with a low strength and increase gradually as your skin builds tolerance to the product. Sensitive skin should use the 2.5% as it may result in irritations. It must be used at night and use sunscreen daily to prevent sunburn, irritation or sensitivity.