Tretinoin is a derivative of vitamin A used as a topical medication for treating acne. Tretinoin shows some effectiveness for treating androgenetic alopecia, or male pattern baldness, when combined with the medication minoxidil, which the U.S. Food and Drug Administration has approved for treating hair loss. Androgenetic alopecia also happens to women, and they can safely use these products as well.
Topical tretinoin is a prescription medication used for treating mild to moderate acne, as well as for other skin problems, such as sun damage and wrinkles. Tretinoin is available in liquid, cream and gel, and it is typically applied at bedtime daily, or once every two or three days. This medication is also known as retinoic acid, and it is the active ingredient in the product Retin-A, as noted by MedlinePlus.
Minoxidil taken orally reduces blood pressure, and when applied topically, it helps stimulate hair growth and prevent hair loss in some users. Available as the brand Rogaine and in generic types, minoxidil increases blood flow in the area of application, increases hair follicle size and lengthens the duration of hair growth, explains the Hair Loss Learning Center. This can result in thicker hair that takes longer to fall out. Most people do not experience hair regrowth from topical minoxidil, but may be able to prevent or slow further hair loss with this product.
Tretinoin is not a significant hair growth stimulant, but applying it to affected areas can enhance the effects of minoxidil. Tretinoin alters the outermost layer of the skin, known as the stratum corneum, so that it does not keratinize, or form a hard compact layer of cells. This allows for better absorption of minoxidil, explains HairSite.
A study published in the April 1990 issue of "Clinical Pharmacology and Therapeutics" investigated the effects of tretinoin on minoxidil absorption in 19 male participants. When minoxidil was administered along with tretinoin cream over 20 days, the minoxidil absorption increased significantly compared with a combination of minoxidil and a placebo cream. Additionally, "Skin and Allergy News" reported in February 2002 that Nia Terezakis, M.D., presented anecdotal cases at the annual meeting of the Pacific Dermatologic Association showing the effectiveness of tretinoin in combination with minoxidil for hair loss treatment.
Minoxidil is associated with side effects, including skin irritation, itching, rashes and dandruff, according to the Hair Loss Learning Center. Excessive doses can lead to overabsorption, which can cause dizziness and rapid heartbeat, but this is unlikely. Tretinoin also can cause side effects, as explained by MedlinePlus, although these effects have been noted by acne patients and not by people using tretinoin for hair loss treatment. Effects reported by some acne users include slight stinging, redness, swelling, blistering and skin crusting.