Two hair specialists explain how the vasodilator extends hair's growth phase and thickens thinning strands, plus the side effects to know.
Minoxidil remains the most evidence-backed ingredient for hair growth, according to trichologists Eva Proudman, resident trichologist for Absolute Collagen, and Tiffany Hall, founder of Trichology, who spoke to Who What Wear.
Minoxidil is a vasodilator, meaning it widens blood vessels to increase blood flow to hair follicles, delivering more oxygen and nutrients. Hall says it also extends hair's growth phase and helps thinning follicles produce thicker strands, working best for androgenetic alopecia, the medical term for male and female pattern hair loss.
Not everyone responds the same way: Hall says minoxidil must be activated by an enzyme that some people have more of than others in their scalp, which is why results vary from person to person. In the UK, topical minoxidil is available over the counter at pharmacies, while oral minoxidil requires a prescription.
Proudman says topical minoxidil is generally well tolerated but can cause scalp irritation, dryness or itching in some people, and said unwanted facial hair growth is uncommon among the roughly 250 patients she sees monthly. She said she prefers topical minoxidil over the oral version, which carries more side effects and is only tolerated at low doses.
