Medically reviewed by Angela Sheddan, DNP, FNP-BC
Written by Our Editorial Team
Last updated 4/23/2021
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 dihydrotestosterone (DHT), a male steroid hormone that binds to receptors in your scalp and -- in genetically susceptible men -- is responsible for hair loss.
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 and the effect DHT hormone has on hair follicles.
In this guide, we’ll explain what DHT is, how it’s produced by your body, and the options that are available regarding how to reduce DHT and limiting its negative effects on your hairline.
But first, let’s answer the question: what is DHT?
DHT, or dihydrotestosterone, is an androgen produced as a byproduct of testosterone. DHT is a fairly powerful male sex hormone that’s responsible for things like forming male genitalia during pregnancy.
In short, DHT is one of the many hormones that makes men, well, men. However, it’s different from other male sex hormones like testosterone in several important ways.
Your body produces DHT as a byproduct of testosterone through the 5α-Reductase enzyme -- an enzyme that converts a certain percentage of your testosterone into DHT in tissue such as the skin, liver, prostate and hair follicles.
If you’re genetically susceptible to hair loss, DHT can bind to receptors in your hair follicles and cause them to shrink, weaken and eventually die. This process is called ‘miniaturization,’ and it eventually leads to a complete end of hair growth in DHT-affected hair follicles.
Interestingly, DHT is an important hormone for hair in other areas of the body, meaning the same hormone that’s responsible for causing male pattern baldness is also responsible for fueling the growth of hair on your chest, back and other areas.
Since DHT is the primary hormone responsible for hair loss in men, an effective way to slow down and prevent hair loss is to block DHT.
You can do this at the follicular level by using a topical hair thickening shampoo or spray to keep DHT off your hair follicles. This is mostly effective, but it doesn’t completely block the DHT from binding to receptors in your scalp.
A more effective method for blocking DHT is to block it at the source. Drugs like finasteride are made to block the conversion of testosterone to DHT by binding to the 5α-Reductase enzyme, preventing your body from producing any DHT in the first place.
We’ll go into more detail on finasteride and other DHT blockers below. For now, when asking yourself, “What is DHT?” just remember that while factors like stress and diet can have a significant effect on your hair, DHT is likely the culprit in your hair loss.
So, what is DHT to finasteride? What relationship do they share?
Data from a study published in the Journal of the American Academy of Dermatology shows that finasteride, in combination with minoxidil, is an effective treatment available for slowing and stopping male pattern baldness.
Finasteride belongs to a category of drugs called 5α-reductase inhibitors. It works by binding to the 5α-reductase enzyme and blocking the enzyme from converting your testosterone into DHT.
The best way to think of finasteride is as a hormonal shield that keeps your testosterone the way it originally was, all while stopping DHT production. Instead of only blocking DHT on your scalp, you’re blocking it at the original source.
On average, a daily dose of 1mg finasteride blocks DHT production enough to stop most hair loss. In certain cases, it can also cause miniaturized hair follicles damaged by DHT to start to grow back.
If you’re starting to notice hair loss and want to take action, the most effective method is to talk to a doctor using our simple online process to see which treatment options are right for you.
For the most part, DHT blocker side effects aren’t very noticeable for most men. The vast majority of people that use drugs like finasteride and topical DHT blockers don’t experience any negative effects -- instead, they notice thicker and healthier hair.
However, some men do experience negative effects from DHT blockers, with finasteride a fairly common culprit. Below, we’ve listed the main side effects of blocking DHT, ranging from positive side effects to potential downsides:
Higher testosterone. Because DHT blockers like finasteride prevent the conversion of testosterone to DHT, they can cause a slight increase in your testosterone production. In this 2003 study, researchers found that finasteride boosted testosterone by a modest amount.
Lower sex drive. Most of the time, finasteride has no positive or negative effect on your sex drive. While taking it, you’ll just feel the same as normal. However, in a small number of men, finasteride can result in a noticeably reduced 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 people also report getting less "morning wood" when on finasteride, possibly due to the lower level of DHT.
Looks scary, right? While the above side effects seem scary, the reality is that the vast majority of men that use DHT blockers like finasteride don’t get serious side effects.
To put things in perspective, a 2012 study of finasteride in Japanese men found that of the 3,177 men given finasteride, only 23 had adverse reactions. Even at five times the regular dosage for preventing hair loss, side effects 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 symptoms to persist 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 hair loss. It’s a bummer, but it’s a part of life.
So, what causes DHT levels to increase? Well, since DHT is a byproduct of testosterone production — as we mentioned above, a certain percentage of your body’s testosterone is converted into DHT via the 5α-Reductase enzyme — it stands to reason that anything that increases your testosterone levels will also increase your DHT levels.
Whether it be from certain vitamins and supplements, to dietary and lifestyle changes, exercising and everything in between, if your testosterone levels are elevated, your DHT levels will likely follow.
However, it’s important to note that this only matters if you have a genetic predisposition to the kind of DHT sensitivity that triggers male pattern baldness.
If you’re starting to notice hair loss, drugs that block DHT are the most powerful weapons you have in your arsenal to slow down and stop it.
Whether or not to take them is ultimately your choice. What’s clear is that the earlier you start to block DHT, the more successful you’ll be in preventing further hair loss. Once the hair is gone, no amount of DHT blocking can bring it back and give you what you once had.
The best way to start blocking DHT production is to use finasteride, along with minoxidil and a shampoo that can block DHT in your scalp.
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