Topical Tretinoin for Hair Growth Promotion

The study tested topical all-trans-retinoic acid (tretinoin) alone and in combination with 0.5% minoxidil on 56 subjects with androgenetic alopecia. After 1 year, 66% of subjects using the combination treatment experienced terminal hair regrowth, while 58% of those using only tretinoin saw some hair regrowth. One female subject with severe alopecia for over 20 years had significant hair regrowth after 18 months of tretinoin use. Tretinoin was found to promote cell proliferation and differentiation in the epithelium and may enhance vascular proliferation, which are important for hair growth. The results suggested further research on retinoids and their synergistic effects with minoxidil.