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Last updated October 25, 2019. 4 minute read

DHT and testosterone: understanding the distinction

DHT is made from testosterone by an enzyme called 5-alpha-reductase and plays a role in male pattern hair loss. Finasteride is an FDA (Food and Drug Administration) approved medication that stops 5-alpha-reductase, which can treat male pattern hair loss and benign prostatic hyperplasia (BPH).

Dr Jefferson Chen Md Written by Dr. Jefferson Chen, MD
Reviewed by Dr. Mike Bohl, MD, MPH

Testosterone: Virtually a synonym for manliness, aggression, and strength. Dihydrotestosterone: A bogeyman feared for taking hair off of your head and putting it on your back. So what’s in this ‘dihydro’ that takes testosterone and turns it into an agent of follicular destruction?

What is DHT?

Dihydrotestosterone (DHT) is a male sex hormone, otherwise known as an androgen, like testosterone. It plays a critical role in male sexual development. In the womb, DHT is responsible for turning genetically male babies physically male. It’s needed for the penis, scrotum, and prostate to develop. During puberty, DHT causes facial hair and body hair (including pubic hair and under-arm hair) to develop and the voice to deepen (Hari Kumar, 2016). DHT has also been implicated in acne, hirsutism (unwanted male-pattern hair growth in women), male pattern hair loss (otherwise known as androgenetic alopecia), benign prostatic hyperplasia (BPH), and prostate cancer.

Learn more about hair loss and prostate health.

Vitals

  • Dihydrotestosterone (DHT) is a male sex hormone that plays a critical role in male sexual development.
  • DHT is made from testosterone by an enzyme called 5-alpha-reductase.
  • DHT plays a role in male pattern hair loss.
  • Finasteride is an FDA (Food and Drug Administration) approved medication that stops 5-alpha-reductase, which can treat male pattern hair loss and benign prostatic hyperplasia (BPH).

How are testosterone and DHT related?

Like we said before, testosterone and DHT are both male sex hormones. When compared to testosterone, DHT is much more potent as a hormone—researchers have estimated that it causes ten times the hormonal effect of testosterone (Azzouni, 2012). DHT is made from testosterone by 5-alpha-reductase, an enzyme that’s present in the skin, prostate, liver, and other areas throughout the body. Medications designed to stop DHT work by shutting down the 5-alpha-reductase and thus stop the conversion of testosterone into DHT.

Learn more about testosterone and low testosterone levels.

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DHT and hair loss

The American Hair Loss Association states that hair loss is “an extremely emotionally distressing disease that makes afflicted patients psychologically vulnerable.” Because of all of the negative connections we have to hair loss, people in the United States spend more than $3.5 billion dollars annually on hair loss treatments (Santos, 2015). There are several different causes of hair loss. Some people have autoimmune disorders while others have nutrient deficiencies. DHT is important in androgenic alopecia (AGA), also called male pattern baldness. It’s the most common reason men lose their hair. Half of all men will start losing their hair by the time they reach age 50, and the problem gets worse with age (Phillips, 2017).

AGA starts in men above the temples and at the vertex, or crown, of the head. As it continues, the hairline recedes at the front, and the area of hair loss at the crown will increase. Hair loss will continue until only a thin rim of hair at the sides and rear of the head will be left (think Danny DeVito.)

Various studies have shown that higher levels of DHT are found in the scalp of men with AGA (Kaliyadan, 2013). In the scalp, DHT shortens the lifecycle of the hair follicle. Because the growth stage of the hair follicle is shortened, the hair follicle becomes miniaturized over time. This eventually leads to visible hair loss.

Stopping DHT

Now that you’re up to speed on what DHT does, how can we stop it? There are two main 5-alpha-reductase inhibitors on the market that block the enzyme that makes DHT, called finasteride (brand name Propecia or Proscar) and dutasteride (brand name Avodart). Both medications are oral tablets and are approved for BPH, but only finasteride is approved by the FDA to treat male pattern hair loss (although the dose is different depending on if you’re using it for BPH or hair loss). Dutasteride is, however, approved for this purpose in Japan and Korea.

How well do these medications work? Studies have shown that finasteride is able to slow balding and hair loss in more than 80% of men and stimulates hair growth in over 60% of men (AAD, n.d.). Just keep in mind that it might take a few months to see results.

What about these DHT-blocking shampoos I’ve been hearing about? There’s no solid evidence that any shampoo is able to block DHT in the scalp. Some shampoos, like ones containing ketoconazole, have been found to help with hair loss, have been theorized to work by blocking DHT or through decreasing inflammation in the scalp. Currently, the only FDA-approved topical medication for hair loss is minoxidil (brand name Rogaine), a medication that treats hair loss not by blocking DHT, but by stimulating more blood flow and nutrients to the hair follicles.

Learn more about hair loss here.