Some types of injury or irritation can activate regenerative processes. A dermatology journal described the case of an old man who had been bald for many years who fell head-first into his fireplace. As his burned scalp healed, new hair grew. In the U.S., experimenters have found that injuring the skin of mice stimulates the formation of stem cells that are able to become hair follicle cells, supporting the regeneration of cells that had been absent. A brief exposure to estrogen, and other stress related signals (nitric oxide, endorphin, prostaglandins) can initiate stem cell proliferation.

This got me thinking, could you really regrow hair with a brief exposure to estrogen? Obviously, putting estrogen/estradiol into your whole body is not great if you're targeting only hair. But you can put in a topical alcohol solution or some kind of lotion to expose your scalp only.

I made an almost joke post about this on X/Twitter but it seems like a really good idea hindered only by the fact that it hinges on a massive (albeit brief) estrogen exposure. For the record, I have NOT researched this elsewhere yet nor is my hair loss significant at all, so if someone could share their opinion (or experience) then that would be awesome.

Edit: Thread on former RPF https://lowtoxinforum.com/threads/topical-estrogen-on-scalp-for-hair.31067/ Not much else there though!