There’s some research to suggest that caffeine may help with hair growth and slow down hair loss., An older 2007 study found that caffeine blocked the effects of dihydrotestosterone (DHT) in male hair follicles. DHT is a hormone that’s linked to hair loss in people of all genders., The caffeine also boosted hair root width and prolonged the growth phase of hair. It had a growth-promoting effect when tested on female hair follicles as well., Because it’s a vasodilator, caffeine may also help improve blood flow to your scalp, promoting hair growth., You can make your own coffee rinse for hair or buy caffeine shampoo.