Does testosterone cause hair loss?

Published on June 1, 2023
Updated on June 1, 2023
Chemical diagrams of testosterone (C19H28O2) and dihydrotestosterone (C19H30O2)
Dihydrotestosterone is the byproduct of the hormone testosterone.

Androgenic alopecia, commonly known as male pattern hair loss, is the main condition that causes men to go bald. This condition is mainly thought to be caused by two factors: genetics and hormones.

Many people believe that testosterone is the hormonal cause of male pattern hair loss. But it’s actually a different androgen, dihydrotestosterone (DHT), that’s thought to be the main hormonal culprit behind this condition.

However – testosterone is essential for the synthesis of DHT. And this is where the relationship between testosterone and hair loss can get confusing, because long-term testosterone injections have resulted in transgender men developing androgenic alopecia.

Does testosterone cause baldness?

Testosterone is not one of the causes of androgenic alopecia. However, its byproduct, dihydrotestosterone (DHT), is thought to be. 

According to a study in the PRS Global Open journal, the 5-alpha reductase enzyme converts testosterone to DHT. DHT then binds to hair follicles, triggering a miniaturization process that causes them to shrink and produce thinner, weaker hair strands. If you’ve started to notice changes to your hairline or you’ve been losing hair around your temples, you’re likely seeing hair follicle miniaturization and some of the early signs of androgenic alopecia.

Blocking the conversion process from testosterone to DHT slows the progression of male pattern hair loss symptoms and helps stop balding. And this is exactly how certain DHT-blocking hair loss treatments – like finasteride and dutasteride – work.  

But of course, DHT isn’t the only culprit behind male pattern baldness. This condition is thought to have a strong genetic component – likely one involving many different genes and mutations. 

Additionally, many other issues have been associated with this hormonal, hereditary form of hair loss. PRS Global Open and Journal of Cosmetic Dermatology studies have highlighted the importance of issues like hair follicle inflammation and overgrown sebaceous glands in the progression of androgenic alopecia.

Testosterone replacement therapy (TRT) and hair loss

TRT refers to testosterone replacement therapy, in which testosterone injections are taken as hormone replacements. These injections are usually given to individuals whose bodies are producing insufficient levels on their own. This can occur in men with several types of health issues, including hypogonadism. 

According to an article in The Lancet: Diabetes and Endocrinology, testosterone injections are also sometimes administered to transgender men who wish to obtain secondary sexual characteristics closer to those of natal males. Trans men may take testosterone injections, as well as other forms of oral and topical TRT. 

According to the Mayo Clinic, hormone replacement therapy in natal men can help bring their testosterone levels back to normal. These injections, sometimes referred to as TRT (testosterone replacement therapy), are able to help improve energy, increase sexual desire, and regain lost muscle mass and bone density. Similar benefits occur for transgender men taking testosterone injections, including increased facial and body hair, a larger proportion of muscle mass, and lowered voice pitch. It can also help stop them from menstruating and alter their hormones.

What are the effects of testosterone injections on hair loss?

Testosterone – whether it is natural or in the form of hormone replacement therapy – should not have any effect on hair health. Only DHT is believed to impact hair follicles and influence the progression of pattern hair loss.

And this certainly seems to be true for natal males. Their scalp hair is not thought to be affected by testosterone injections, though the Mayo Clinic says that hormone replacement therapy can help increase scalp and body hair. In contrast, testosterone injections have been shown to affect the hair of transgender men. And when taken long-term, they have even been shown to cause pattern hair loss in some individuals.

According to The Lancet: Diabetes and Endocrinology article, the chance of a transgender male developing androgenic alopecia after receiving testosterone injections seems to vary. Some studies have reported pattern hair loss symptoms in as much as 64 percent of trans men, while others have reported as little as 17 percent. These numbers are in line with a report in The British Journal of Dermatology, which found that testosterone-induced androgenetic alopecia was present in about two-thirds of trans men.  

“Hair loss was more common among trans men on masculinizing hormone therapy than those not on hormone therapy… Participants also reported significant worsening of hair loss after starting testosterone therapy.”

- Dr. Caitlyn T. Reed, MD

As published in The British Journal of Dermatology.

Be aware that testosterone replacement therapy isn’t just available as an injection. According to an article in the American Journal of Clinical Dermatology, testosterone is also available as an oral drug, gel, and patch. 

It may seem strange that testosterone replacement therapy increases the chances of hair loss in transgender men, but not natal males. However, this may be because natal male individuals have always had high levels of testosterone circulating in their bodies. 

Transgender male individuals were born as natal females. Therefore, it may be the dramatic increase in testosterone, to levels comparable to those of natal males – and the consequent rise in DHT levels – that’s causing the relationship between testosterone and balding. Essentially, transgender men are experiencing high DHT on TRT – an issue that would potentially go away if they stopped TRT injections.

Treating male pattern hair loss 

Hair loss is unpleasant. The good news is that as the most common cause of balding, androgenic alopecia has a variety of treatment options you can choose from. The Food and Drug Administration has approved three treatment options for pattern hair loss: minoxidil, finasteride, and low-level laser therapy. 

According to StatPearls Publishing, finasteride, an oral medication that’s taken once a day, is the only one of the three FDA-approved hair loss treatments that affects your hormone levels. However, this prescription-only drug is only FDA-approved for natal males. It has yet to be approved for women and should not be used by transgender men who intend to have children.

There are very few studies on finasteride’s safety for transgender men. Additionally, finasteride’s properties may have negative effects on transgender males taking hormone replacement therapy, blocking TRT’s desired effects. The American Journal of Clinical Dermatology article also says that this drug is sometimes used off-label as a hormone blocker for feminization purposes (for male to female transgender individuals).

Both minoxidil and laser hair therapy are approved for use by men and women. They don’t affect hormones, making them much safer hair loss treatments for transgender individuals. Both of these are also over-the-counter hair loss treatments – so unlike finasteride, you won’t need a prescription to buy them.

Minoxidil works as a vasodilator, increasing blood flow to your scalp and hair follicles. This encourages more blood and nutrients to reach them, which in turn allows for healthier, stronger hair to grow. The American Journal of Clinical Dermatology article says that this topical treatment can be safely used by both natal and trans men. The 5 percent solution of minoxidil is thought to be most effective. 

Laser hair therapy is available in clinics, but can also be purchased in the form of a device. Low-level light therapy caps, combs, brushes, helmets, and headbands can be purchased for use at home. This biostimulatory light therapy treatment is able to help stop hair loss and encourage new, healthy hair growth.

​​Does high testosterone cause hair loss?

High testosterone does not cause hair loss. Testosterone is not the hormone culpable for hair loss. It’s dihydrotestosterone, an androgen that is produced from it, that is responsible. 

However, increasing testosterone levels can result in hair loss symptoms in certain men. In particular, some transgender men who take testosterone injections have found that this hormone replacement therapy causes androgenic alopecia, or makes existing hair loss worse. 

But either way, testosterone is not directly culpable for this problem. It’s still the conversion from testosterone to dihydrotestosterone – and the resulting increase in DHT levels – that’s causing these symptoms to appear. 

Blocking DHT is an FDA-approved strategy that works by preventing the conversion from occurring. Just one pill of finasteride each day has been shown to help stop pattern hair loss symptoms from getting worse.

However, this oral medication is only FDA-approved for men, and transgender men may not find it suitable for their needs. This hormone-blocking drug has the potential to affect their hormone replacement treatments and is not safe for trans men who want to have children. 

Instead, transgender individuals may want to consider a different FDA-approved hair loss treatment, like minoxidil or low-level laser therapy. Both of these over-the-counter treatments can be used by men and women and won’t affect hormone levels.  

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.


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