Testosterone Therapy and Hair Loss in Women: Is It Really a Problem?

Part 1 in a Series on Hair Loss in Midlife Women.

“I’d take testosterone, but I don’t want to lose my hair.” - Mary, age 52.

When women consider hormone replacement therapies during menopause, one common fear often stands in the way of exploring testosterone supplementation: "Will it make my hair fall out?"

This concern isn't surprising. For decades, the medical community and popular media have perpetuated the notion that testosterone inevitably leads to hair loss in women. After all, men have higher testosterone levels and experience more baldness—the connection seems obvious.

But is this widely accepted "truth" really a problem? Or is it one of those “mountains out of a mole-hill” or even “mountains out of associations with a different mountain” type situations that we so often see in medicine?

The Science of Hair Loss: Testosterone vs. DHT

To understand the relationship between testosterone and hair loss, it is first necessary to distinguish between testosterone itself and its more potent metabolite, dihydrotestosterone (DHT).

When most people blame "testosterone" for hair loss, they're actually referring to the effects of DHT. In hair follicles and sebaceous glands, testosterone can be converted to DHT through a reaction catalyzed by the enzyme 5-alpha-reductase. It's DHT—not testosterone itself—that binds to receptors in scalp follicles, potentially causing them to shrink to the point where they can no longer grow healthy hair.

In men, there’s a strong causal link between elevated DHT levels and male pattern hair loss (aka androgenic alopecia). DHT binds the androgen receptors in the scalp follicles, triggering miniaturization (shrinking) and shortening of the hair growth cycle. In these men, we see the “male pattern” of hair loss, affecting the front, temples, top, and crown.

Administering 5α-reductase blockers, such as finasteride (Propecia), effectively slows or reverses hair loss in 80-90% of men, as they reduce the amount of testosterone that is metabolized into DHT.

Are Women Just “Small Men”?

DHT sensitivity and elevated DHT levels contribute to hair loss in men, as supported by multiple studies. But, as we know quite well by now but somehow keep forgetting, women are not small men. Our physiology is different. It’s unwise to extrapolate male-centric data on anything into women because we don’t always behave as men do. Much to their dismay!

While female pattern hair loss (FPHL) looks similar to male pattern hair loss (MPHL, aka “androgenic alopecia”) under a microscope, the role of androgens in the development of FPHL is much less clear than MPHL. In fact, while more than 50% of women will experience hair loss during their lifetimes, only 10-30% of female hair loss in midlife is associated with clinically measurable androgen excess (ie, high testosterone or high DHT). In a 2005 study, it was found that fewer than 10% of women with biopsy-confirmed FPHL exhibited biochemical or clinical signs of virilization, including increased body hair, elevated androgens, and acne.

This poor correlation between high androgens and most forms of FPHL may explain why anti-androgens (ie, DHT blockers, such as finasteride) show inconsistent results in women despite being highly effective in men.

In an article in balance menopause, trichologist Jane Martins of Philip Kingsley said, “Although it has been well established that DHT plays a significant role in male pattern hair loss, the role of DHT in female pattern hair loss remains unclear.”