Estrogen Therapy and Hair Growth

For the male readers of this blog, estrogen (also known as oestrogen) is not something that one would consider to be of interest. For one, estrogen is a female hormone. What male in his right mind would want to start taking estrogen and get female secondary sexual characteristics?

Having said that, estrogen does have some beneficial properties for the heart. It is also though to be one of the main reasons behind why females outlive males. However, I would still pass on supplementing with the hormone.

Estrogen Hormone Therapy and Hair Growth

The reason I decided to write a post on estrogen is because I recently read an extremely interesting 2012 interview with Dr. George Cotsarelis. While the main part of the interview is devoted to the oft discussed PGD2, there are several other interesting subjects discussed. The second page of the interview is what really surprised me in a good way.

In the first part of this interview, Dr. Cotsarelis discusses the old and well known Dr. James Hamilton study from the 1950s. In this research, it was found that men who were castrated before puberty (eunuchs) never went bald. However, upon being given testosterone, those with a family history of baldness still started to loose hair.

The second part of the interview is more interesting. It covers the fact that even after someone has lost much of his hair due to androgenic alopecia, he can regrow a lot of it when given estrogen (after castration)!

This point is supposedly verified by many studies on Male-to-Female (MTF) transitioning transgender persons. Such patients show hair regrowth after their being castrated and getting on estrogen hormone replacement therapy (HRT). Usually with the addition of an anti-androgen such as Spironolactone.

While I do not think any of us men want to get castrated or take estrogen (estradiol), this is still an incredible finding. One of the best examples is in the before and after image below from this study.

Estrogen Treatment Hair Growth
Estrogen (Estradiol) Treatment Hair Regrowth. Source: Journal of the American Academy of Dermatology.

Note that both estrogen and progesterone extend the anagen growth phase cycle of hair follicles. In contrast, testosterone and dihydrotestosterone (DHT) do the opposite and shorter the hair growth phase. Make sure to also read my post on how finasteride impacts testosterone and estrogen levels.

Hair Regrowth Difficulties

Over the years, I have read a number of articles in which doctors and professionals seem to suggest that once hair is gone (turns vellus), it can never return. This is also why Finasteride and Minoxidil virtually never bring back any significant amount of hair for someone who is mostly or entirely bald. However, it seems like hair can regrow in fully bald areas of the scalp in some instances.

There have been anecdotal reviews on Dutasteride actually regrowing long disappeared hair. But these have been few and far between. Over a decade ago, Dr. Marty Sawaya caused an insane level of excitement on hair loss forums when she reported that one of her older patients gained back most of his lost hair when on Dutasteride. But that whole episode was controversial and not replicated.

More recent research suggests that a balding scalp still has all the follicle stem cells intact. But certain progenitor cells have become depleted. Basically, the cells are there, but the activity is not there. Dr. Cotsarelis has suggested that perhaps blocking PGD2 will allow the stem cells to make progenitor cells again. However, this is not a certainty, and neither is hair regrowth guaranteed once PGD2 is inhibited.

I suspect that this powerful impact of estrogen on hair regrowth is still not strong enough to grow back all of one’s lost hair. This is because many older balding MTF transsexuals seem to get hair transplants even after getting castrated and beginning estrogen therapy.

Finally, for men who take Finasteride (brand names Propecia, Proscar, Finpecia), one potential side effect is increased estrogen levels. This sometimes results in the dreaded gynecomastia (male breast enlargement), along with fat gain in other parts of the body. Their are numerous complaints on hair loss forums about this side effect.