According to Dr. Andrea Suarez, there are various types of hair loss, but the studies conducted on the anti-aging ingredient tretinoin and its relation to thinning hair have mainly focused on androgenetic alopecia. Suarez further pointed out the limited scale of these studies, with many of them being small and one even involving gerbils instead of human subjects.
A 2019 study on androgenetic alopecia published in Dermatologic Therapy indicated that the most effective approach for hair regrowth might involve the combined use of tretinoin and minoxidil. Minoxidil is a common ingredient used in treatments for certain types of baldness, such as androgenic alopecia. As trichologist Helen Reavey explained to Refinery29, “If you don’t have androgenic alopecia, minoxidil has no purpose.” Ultimately, hair thinning can be caused by numerous factors, and what works for one person may not work for everyone.
Additionally, if you have used retinol for skincare to address acne or anti-aging concerns, you may be aware that it can cause irritation and sensitivity, particularly at the start of your regimen. Tretinoin, which can lead to side effects like burning, peeling, redness, skin irritation, and dryness, should only be used under the guidance of a doctor (per Mayo Clinic). Suarez also mentioned that minoxidil can irritate the skin. Therefore, combining tretinoin and minoxidil on your hairline to prevent thinning may result in increased irritation and could even cause irritant contact dermatitis.