Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 9/30/2022
If you’ve noticed your hair starting to thin or recede, it’s easy to stress over what’s causing it to happen. Is it stress? A bad diet? Unlucky genetics? Or is it a lifestyle factor you can fix through a change in behavior?
The reality is that hair loss in men is primarily caused by a combination of genetic factors and a male steroid hormone called dihydrotestosterone (DHT), which can bind to receptors throughout your scalp and interrupt your natural hair growth cycle.
DHT can seem complicated, but its role in hair loss is fairly easy to understand once you have a basic knowledge of how your body produces DHT, as well as the damaging effects that DHT can have on your hair follicles if you’re genetically susceptible to its effects.
Below, we’ve explained what DHT is, how it’s produced by your body and the effects it can have on healthy hair growth.
We’ve also covered your options for reducing DHT levels, preventing hair loss and -- if you have visible hair loss already -- stimulating new hair growth.
DHT, or dihydrotestosterone, is a type of androgen hormone that’s produced by your body as a byproduct of testosterone.
Androgens are hormones that produce male characteristics. They’re responsible for maintaining certain aspects of your sexual health, as well as your male secondary sex characteristics, which includes features such as a deep voice, as well as your body hair and bone structure.
Although testosterone is your body’s primary male sex hormone, DHT also plays a major role in numerous vital functions within your body. Prior to birth, it helps to promote proper development of your genitals, and during puberty, it’s responsible for your facial and body hair.
In short, DHT is one of the many hormones that makes men, well, men. However, although it’s named similar to testosterone, it’s different from other male sex hormones in several important ways.
Your body produces DHT as a byproduct of testosterone through the 5α reductase enzyme, an enzyme that converts a small percentage of your testosterone into DHT in bodily tissue such as your skin, liver, prostate and hair follicles.
In most men, testosterone is much more abundant than DHT. According to research, the typical level of DHT in your bloodstream is only around 10 percent of your level of testosterone.However, because of its potency, DHT can have significant effects within your body, even if the total amount of this hormone that circulates in your bloodstream is relatively small.
If you’re genetically susceptible to male pattern baldness, DHT can attach to receptors referred to as androgen receptors, which are found inside your hair follicles.
When DHT attaches to these receptors, it can cause them to undergo a process referred to as “miniaturization,” in which the hair follicles gradually shrink, wither and eventually stop growing new hairs.
To understand how this can affect your hair, it’s important to go over the basics of how your hair grows in the first place.
Every hair on your body, from your scalp to your arms and legs, grows as part of a multi-phase cycle that’s referred to as the hair growth cycle.
This cycle involves an anagen phase, or growth phase, during which your hair grows to its full length. Each anagen phase can last anywhere from only a few months (for your body hair) to several years (for your scalp and facial hair).
After the anagen phase, your hair enters the catagen phase, during which it transitions from a state of active growth to dormancy. It then enters into the telogen phase, during which it rests as a new hair grows from the follicle to replace it.
This continual, year-round process allows you to maintain a full head of hair even as you shed old hairs and grow new ones.
When DHT miniaturizes your hair follicles, it shortens the anagen phase and prevents your hair from growing properly. Over time, hairs affected by DHT become thinner and shorter, eventually resulting in hair that’s unable to penetrate through the outermost layer of your skin.
As your hair becomes affected by DHT, you may notice that certain areas of your scalp begin to look thinner than before.
Interestingly, DHT is also an important hormone for hair in other areas of the body, meaning the same hormone that’s responsible for male pattern baldness is also responsible for the growth of hair on your chest, back and legs.
So, if DHT is responsible for male pattern baldness and all men produce DHT as a byproduct of testosterone, why do some men go bald early in life while others are able to effortlessly maintain a full head of hair well into old age?
Just like your genes play a major role in determining your height, hair color, eye color and other physical characteristics, genetic factors have a massive influence on how susceptible you are to male pattern baldness.
After all, male pattern baldness is commonly referred to as androgenetic alopecia -- a word that is made by fusing together “androgenic” and “genetic.”
Experts believe that some men go bald faster than others due to a genetic predisposition to the effects of androgens such as DHT.
In other words, some men appear to have hair follicles that are more sensitive to the effects of DHT than others, meaning they miniaturize and stop growing new hairs faster when DHT binds to receptors in the scalp.
Research also suggests that men affected by male pattern baldness tend to have higher levels of DHT than their peers, as well as greater concentrations of androgen receptors in the scalp.
This means that if you’re very susceptible to hair loss, you may not just be more sensitive to the effects of DHT than your peers -- your body may also be more prone to converting testosterone into DHT, particularly in your hair follicles.
It’s worth noting that the effects of DHT on hair follicles don’t only occur in men. Women are also affected by DHT. In fact, many women start to develop some signs of DHT-related hair loss after middle age, particularly as they enter into menopause.
When this type of hair loss occurs in women, it’s typically referred to as female pattern hair loss, or FPHL.
However, because women only produce a small fraction as much testosterone as men, this type of hair loss isn’t as common and is generally mild in severity.
Testosterone and dihydrotestosterone sound very much alike. However, in spite of their related origins, there are several key differences between testosterone and DHT when it comes to how they affect your health, as well as how essential they are for normal bodily functioning.
As a man, testosterone is a critical hormone for your wellbeing throughout your life. Maintaining a healthy level of testosterone helps to:
Promote a normal sex drive
Keep your bones strong and healthy
Promote muscle growth and strength
Stimulate red blood cell production
Prevent excessive body fat levels
During childhood and puberty, testosterone also plays a role in the development of secondary sex characteristics, such as your voice, height, facial hair, skeletal muscle mass and red blood cell count.
Put simply, testosterone is essential for optimal health both when you’re developing physically, as well as throughout your life as an adult. Low testosterone is associated with a wide range of symptoms, including many that can affect your wellbeing and quality of life.
Dihydrotestosterone, on the other hand, is important during childhood and puberty, but doesn’t play such a major role in your ongoing wellbeing as an adult.
In fact, DHT doesn’t play any significant role in the physiology of adults. As an adult, the major effects of DHT include contributing to unwanted prostate enlargement and binding to receptors in your scalp and causing pattern hair loss.
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Because DHT is the main hormone responsible for hair loss in men, the most effective way to slow down and prevent hair loss is to block DHT.
If you’ve ever spent time browsing the men’s shampoo section of your local drug store, you’ve likely seen shampoos that are marketed as DHT blockers. These products contain ingredients that wash away excess DHT from your scalp, which may help to protect against hair loss.
In fact, our Hair Thickening Shampoo features the active ingredient saw palmetto, which could help to prevent DHT buildup on your scalp and protect your hair follicles.
This approach is mostly effective, but it doesn’t completely block the DHT from attaching to the receptors in your scalp and causing follicular damage.
A more effective method for blocking DHT and protecting your hair follicles is to stop your body from producing it in the first place.
You can do this using medications like finasteride, which work by inhibiting the effects of certain enzymes that your body uses to convert testosterone into DHT.
Finasteride, which is available as a generic medication and under the brand name Propecia®, is a prescription medication that’s used to treat male pattern baldness.
You may have heard of finasteride before if you’ve looked into hair loss treatments. It’s part of a class of drugs referred to as 5α reductase inhibitors, which work by directly blocking the effects of the enzyme that’s responsible for the conversion of testosterone into DHT.
This enzyme, called 5-alpha reductase, is found in certain types of tissue throughout your body, including your scalp.
By preventing 5-alpha reductase from working, finasteride drastically lowers the total amount of DHT your body produces. Used daily, a normal dose of finasteride can reduce your DHT levels by as much as 70 percent.
This reduction in DHT levels means that your hair follicles are no longer under constant damage due to the effects of DHT. You can think of finasteride as working almost like a shield that blocks DHT from miniaturizing your hair follicles and contributing to hormonal hair loss.
Instead of only blocking DHT on your scalp, like a shampoo can, you’re blocking it at the original source.
Thanks to its effects on DHT levels, finasteride can reduce the severity of hair loss and help you to maintain a fuller head of hair. Many men who use finasteride find that their hair loss comes to a complete halt during treatment, or that certain areas show signs of hair regrowth.
Using finasteride is simple. Since it’s available as a daily-use tablet, all you need to do is take a single tablet of finasteride each day to reduce the severity of your hair loss. You can do this at any time of day, provided you stick to a consistent daily schedule for your medication.
Although finasteride starts to work right away, it can take several months before you’ll be able to see any changes in your hair’s thickness, growth and coverage.
Many men show improvements after using finasteride for three months, with the most noticeable improvements usually visible after around one year of consistent use.
The vast majority of men that use drugs like finasteride and topical DHT blockers don’t have any negative effects -- instead, they usually just notice thicker and healthier hair.
However, a small percentage of men who use DHT blockers like finasteride do experience some side effects. These can range from a mild increase in testosterone levels to sexual performance issues such as erectile dysfunction (ED) and a reduced sex drive.
Potential side effects of medications like finasteride include:
Higher testosterone levels. Because DHT blockers like finasteride stop the conversion of testosterone to DHT, they may contribute to a slight increase in your total testosterone levels.
In a study published in the journal Urology in 2003, researchers found that long-term use of finasteride was associated with a modest increase in testosterone.
Lower sex drive. Most of the time, finasteride has no positive or negative effect on your sex drive. While taking it, you’ll feel the same as normal. However, in a small number of men, finasteride can result in a noticeably reduced level of interest in sex.
Weak erections. Just like reduced sex drive, this is a rare side effect that affects a small number of finasteride users. Some men report getting less “morning wood” while taking finasteride, possibly due to lower levels of DHT.
Looks scary, right? While the side effects listed above can seem scary, the reality is that the vast majority of men that use DHT blockers such as finasteride don’t get serious side effects.
To put things in perspective, a 2012 study of finasteride in Japanese men found that out of the 3,177 men who used finasteride, only 23 developed adverse reactions. Even at five times the regular dosage for preventing hair loss, side effects from finasteride are rarely reported.
It’s also worth noting that in the rare event of sexual side effects occurring, they’ll almost always stop once you come off finasteride. It’s extremely rare for any negative effects to continue if you don’t actively take a DHT blocker.
If you’re genetically predisposed to DHT sensitivity, any kind of increase in your DHT levels may potentially heighten your risk of dealing with pattern hair loss. It’s a bummer, but it’s a part of life.
So, what could cause your DHT levels to increase? Well, since DHT is produced as a byproduct of testosterone, it stands to reason that anything that contributes to higher testosterone levels is also likely to contribute to more DHT.
As we’ve covered in our guide to increasing your testosterone levels, a variety of factors all play a role in testosterone production.
These include minimizing stress, exercising frequently, maintaining a healthy weight, getting at least seven hours of nightly sleep, eating a balanced diet and avoiding harmful habits, such as drinking alcohol excessively.
Some types of medication, such as testosterone injections used to treat low testosterone levels, may also contribute to elevated levels of DHT and hair loss.
However, it’s important to keep in mind that this only matters if you have a genetic predisposition to the kind of DHT sensitivity that causes androgenic alopecia, or male pattern baldness.
Because of its effects on your hair follicles, DHT is the primary hormone responsible for pattern hair loss in men. As such, it makes sense to block it if you’re starting to develop the early signs of male pattern baldness.
Because it works by directly targeting the enzyme that produces DHT, finasteride can be one of the most powerful weapons in your arsenal for slowing down and stopping hair loss.
In addition to preventing DHT production, you can further reduce hair loss and stimulate growth by using topical medications such as minoxidil, which is thought to stimulate blood flow to your scalp.
Interested in getting started? Take part in a hair loss consultation to learn more about your best options for preventing hair loss, stimulating hair growth and maintaining a fuller, thicker head of hair throughout your life.