Does testosterone cause hair loss?

There are many causes of hair loss—aging, hair care products, certain health conditions, and even medication side effects. But hormones like testosterone (the primary male sex hormone) can also be associated with hair loss, particularly a common form called pattern baldness.

Female or male pattern hair loss, also called androgenic alopecia or androgenetic alopecia (AGA), develops gradually as a receding hairline or a bald spot on the top of the head. Men are more affected by this condition—50 million men as opposed to 30 million women, according to the National Institutes of Health. This condition has also been linked to menopause in women and conditions like insulin resistance and polycystic ovary syndrome (PCOS), a common condition characterized by hormonal imbalance in women.

Testosterone and hair loss

Although the relationship between hair loss and sex hormones is complex, androgen hormones like testosterone may play a role in the hair cycle and hair follicle structure. However, the impact of androgens on hair depends on where the hair is located in the body. For instance, androgens tend to have a stimulatory effect on hair found on the face, the armpit, the pubis, and the chest but exert an inhibitory effect on the hair follicles in the region of the scalp. Meaning, testosterone encourages hair growth in certain places while limiting it in others.

Androgens are male hormones that regulate the development and maintenance of male sexual characteristics but are also produced in small amounts in the female body. Testosterone is the most common androgen. Other forms of androgen in the body include:

• Dehydroepiandrosterone (DHEA)
• Androstenedione
• DHEA sulfate (DHEA-S)
• Dihydrotestosterone (DHT)

“Testosterone can contribute to hair loss, particularly through its more potent form, dihydrotestosterone (DHT),” says Hannah Kopelman MD, a dermatologist at Kopelman Hair Restoration in New York, New York. DHT is a byproduct of testosterone. “Testosterone is converted into DHT by the enzyme 5-alpha-reductase,” Dr. Kopelman explains. “This occurs in various tissues, including the scalp.” DHT plays a role in regulating the hair growth cycle and, in some individuals, can contribute to the shortening of the anagen phase.

Here is an overview of the hair follicle growth cycle:

• Anagen: This is the growth phase when the hair follicles form the cells that give rise to hair. This phase can last for several years.
• Catagen: This phase signals a transition from the growth phase to the inactive phase. It is also a period when the follicles renew and can last for a few weeks.
• Telogen: This is the inactive or resting phase. During this phase, the hair shafts are not growing, and depending on the location of the hair, the phase can last from a few weeks to close to 12 months. 
• Exogen: This is the phase where the existing hair is pushed out and shed. It is typical to shed up to 100 hairs a day.

Role of dihydrotestosterone (DHT) in hair loss

During male fetal development, DHT plays a vital role in the development of male external genitalia. However, at puberty, it is involved in the development of the prostate and contributes to the male pattern of hair growth.

While testosterone is a primary androgen and can bind to androgen receptors in hair follicles, studies have indicated that DHT, which is its active metabolite, is more potent and has about two to five times more binding affinity to androgen receptors than testosterone. “In individuals predisposed to male pattern baldness, this binding can cause hair follicles to miniaturize, shortening their growth phase and leading to hair thinning and loss,” Dr. Kopelman notes, adding that there are other key factors that may predispose a person to this form of hair loss.

For instance, a 1998 study published in the Journal of Endocrinology showed that hair follicle cells in people with balding scalps have higher levels of androgen receptors than the follicle cells in people with non-balding scalps. This means the presence of receptors also plays a role in androgen effects on the hair. In people with fewer androgen receptors, a high testosterone or DHT level may not cause hair loss. This is also where genetic variation comes into play. Scientists believe that some people inherit a variant of the androgen receptor (AR) gene that is more susceptible to the effects of testosterone and DHT on their scalp hair.

In a nutshell, people with higher levels of testosterone tend to have higher levels of DHT because more of the testosterone is converted to DHT. But this doesn’t always result in hair loss. Hair loss will most likely occur if those people have a variant of receptors in their hair follicles that are highly sensitive to androgen.

But how can a person tell that their hair loss is linked to testosterone or DHT? According to William Gaunitz, certified trichologist and founder of Advanced Trichology in Tempe, Arizona, signs of hormonally related hair loss due to dihydrotestosterone may include:

• Hair loss directly on the top of the scalp more than on the sides
• Excessive oil on the top of the scalp
• Miniaturization, or constriction, of the hair follicles on the top of the scalp
• Spontaneous adult acne

Gaunitz adds that women may experience hair growth in non-typical areas of the body, such as the chin or chest. People should consider seeking medical advice if they experience these symptoms.

Other factors that contribute to hair loss

Other factors that can contribute to thinning hair or hair loss include: 

• Genes: Inheriting genes that make the hair follicle susceptible to shrinking and thinning can contribute to hair loss. A family history of pattern hair loss on either side of the family, male or female, can predispose a person to hair loss.
• Age: As people get older, their hair growth tends to slow down. Many of the hair follicles stop producing new hair at that point. Alongside hair thinning and hair loss, some people may notice changes in the diameter of their hair fibers, hair density, and hair color. 
• Nutrient deficiency: Aside from their effect on health and well-being, deficiency of micronutrients like iron, zinc, biotin, and magnesium may contribute to hair loss or impact recovery from hair loss disorders. 
• Alopecia areata: This is a rare condition that occurs when the body’s immune system attacks the hair follicles, causing loss of scalp hair or body hair. 
• Pregnancy and childbirth: Some people experience hair loss after childbirth, and according to the American Academy of Dermatology Association (AAD), this is normal. It happens as a result of a drop in estrogen levels and is often temporary. 
• Medications/treatments: Certain medications or treatments, such as cancer therapy, may cause hair loss. Arava (leflunomide) and methotrexate, used for treating arthritis, can also cause hair loss in some people. 
• Hair care products and styling methods: Certain chemicals used to produce hair care products, like shampoos, may cause hair loss. Also, hair styling practices such as using dyes and straighteners can cause contact dermatitis, chemical burns, or scarring, which may contribute to hair breakage.
• Stress and illnesses: Hair loss can happen when a person is experiencing stress. Medical conditions like thyroid disease, scalp infections, and plaque psoriasis can also contribute to hair loss.

Myths about testosterone and hair loss

Although there is a link between testosterone and hair loss, there are also many incorrect beliefs about the two. Here are three of the most common myths:

1. All bald men have high testosterone levels. While testosterone sometimes contributes to hair loss or baldness, high testosterone does not always equal baldness. Testosterone primarily affects the hair when its metabolite form, DHT, is high in people who have high androgen-sensitive receptors in their hair follicles. This means male pattern baldness can also occur in people with lower circulating levels of testosterone.
2. Testosterone has no effect on hair loss. This is not entirely true. DHT is formed from testosterone, and according to a resource from the Society for Endocrinology, nearly 10% of the testosterone produced by adults daily is converted to DHT.
3. Weight training increases testosterone, which leads to hair loss. Studies show that resistance exercises like weight training can elevate blood testosterone levels. But this is only transient and unlikely to cause long-term effects like hair loss.

Notably, in some men with low testosterone levels, “adding back some minor levels of testosterone, e.g., using testosterone replacement therapy (TRT), can improve hair growth,” Gaunitz explains. “However, if a certain threshold is exceeded, then hair loss may ensue.”

Preventing and treating testosterone-related hair loss 

If you are experiencing hair loss, there are many hair loss treatments you can explore, including prescription medications, medical interventions, and lifestyle changes. Your options include:

• Propecia (finasteride) is an FDA-approved DHT blocker that acts by blocking the action of the enzyme that converts testosterone to DHT. Healthcare providers sometimes prescribe it to prevent or treat this type of hair loss.
• Rogaine (minoxidil) enables hair follicle growth by shortening the telogen phase and maintaining the anagen phase.
• Hormonal therapies, such as spironolactone, a prescription medication that decreases testosterone production, and bicalutamide, which is a nonsteroidal, antiandrogen medication also used to treat prostate cancer, can both help with hair loss.
• Avodart (dutasteride) is sometimes used as an off-label treatment for hair loss.
• Light therapies, including low-level laser therapy and light-emitting semiconductor devices, may help to stimulate hair growth, but more research is needed.
• Regenerative medicine therapies like injecting Mesenchymal stem cell-derived exosomes (MSC‐Exosomes) have shown promise in stimulating hair regrowth.
• Hair transplant surgery and augmentation therapy, such as micro-needling, are also options to try if other treatments have failed to create hair regrowth.
• Supplements and over-the-counter treatments, such as nutraceuticals that contain certain bioavailable botanical extracts and plant-based oils like tea tree oil and coconut oil, may help prevent hair loss.
• Lifestyle changes can also help prevent excess hair loss and promote healthy hair, such as eating a healthy diet, avoiding the use of high-heat styling tools, avoiding hair products containing harsh chemicals, reducing stress, and staying hydrated.

The bottom line: Hair loss causes are complex but may be treatable 

Testosterone alone may have little to no effect on scalp hair. However, when converted to DHT, this hormone may induce hair loss, particularly in people with a specific gene that is highly sensitive to androgens.

While DHT-related hair loss is common, many other things can contribute to hair loss. People experiencing increased hair loss should consider speaking with a healthcare provider, who will ask relevant questions and make a proper diagnosis. Depending on the cause of their hair loss, they may also be referred to experts like a dermatologist, a trichologist, or an endocrinologist for treatment.