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 has on hair follicles.
In this guide, we’ll explain what DHT is, how it’s produced by your
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 growth 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, the most 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 DHT blocking shampoo or spray to keep DHT off your hair follicles. This is
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, just remember that while factors like stress and diet can have a significant effect on your hair, your hair loss is most likely caused by a genetic sensitivity to dihydrotestosterone.
Finasteride and DHT
Data from a study published in the Journal of the American Academy of Dermatology shows that finasteride, in combination with minoxidil, is the most 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
Remember earlier, when we said that DHT binds to receptors in the prostate? Finasteride was actually originally designed as a treatment for prostate growth. It wasn’t until the medical study period that Merck, the drug’s creator, discovered it also stopped male pattern baldness.
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.
What are the Side Effects of Blocking DHT?
For the most part, blocking DHT doesn’t produce any noticeable side effects 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.
If you compete in tested sports, you should be aware that this effect on testosterone production means that finasteride could be on the banned drug list.
- 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.
Should You Block DHT?
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.
This article was reviewed by Brendan Levy, MD.
Important Safety information
IMPORTANT SAFETY INFORMATION
Finasteride is for use by MEN ONLY and should NOT be used by women or children.
Read this Patient Information before you start taking Finasteride and each time you get a refill. There may be new information. This information does not take the place of talking with your healthcare provider about your medical condition or treatment.
What is Finasteride?
Finasteride is a prescription medicine used for the treatment of male pattern hair loss (androgenetic alopecia).
It is not known if Finasteride works for a receding hairline on either side of and above your forehead (temporal area).
Finasteride is not for use by women and children.
Who should not take Finasteride?
Do not take Finasteride if you:
- are pregnant or may become pregnant. Finasteride may harm your unborn baby.
- Finasteride tablets are coated and will prevent contact with the medicine during handling, as long as the tablets are not broken or crushed. Females who are pregnant or who may become pregnant should not come in contact with broken or crushed Finasteride tablets.
- If a pregnant woman comes in contact with crushed or broken Finasteride tablets, wash the contact area right away with soap and water. If a woman who is pregnant comes into contact with the active ingredient in Finasteride, a healthcare provider should be consulted. If a woman who is pregnant with a male baby swallows or comes in contact with the medicine in Finasteride, the male baby may be born with sex organs that are not normal.
are allergic to any of the ingredients in Finasteride. See the end of this leaflet for a complete list of ingredients in Finasteride.
What should I tell my healthcare provider before taking Finasteride? Before taking Finasteride, tell your healthcare provider if you:
have any other medical conditions, including problems with your prostate or liver
Tell your healthcare provider about all the medicines you take, including prescription and nonprescription medicines, vitamins, and herbal supplements.
Know the medicines you take. Keep a list of them to show your healthcare provider and pharmacist when you get a new medicine.
How should I take Finasteride?
- Take Finasteride exactly as your healthcare provider tells you to take it.
- You may take Finasteride with or without food.
If you forget to take Finasteride, do not take an extra tablet. Just take the next tablet as usual.
Finasteride will not work faster or better if you take it more than once a day.
What are the possible side effects of Finasteride?
decrease in your blood Prostate Specific Antigen (PSA) levels. Finasteride can affect a blood test called PSA (Prostate-Specific Antigen) for the screening of prostate cancer. If you have a PSA test done you should tell your healthcare provider that you are taking Finasteride because Finasteride decreases PSA levels. Changes in PSA levels will need to be evaluated by your healthcare provider. Any increase in follow-up PSA levels from their lowest point may signal the presence of prostate cancer and should be evaluated, even if the test results are still within the normal range for men not taking Finasteride. You should also tell your healthcare provider if you have not been taking Finasteride as prescribed because this may affect the PSA test results. For more information, talk to your healthcare provider.
There may be an increased risk of a more serious form of prostate cancer in men taking finasteride at 5 times the dose of Finasteride.
The most common side effects of Finasteride include:
- decrease in sex drive
- trouble getting or keeping an erection
a decrease in the amount of semen
The following have been reported in general use with Finasteride:
- breast tenderness and enlargement. Tell your healthcare provider about any changes in your breasts such as lumps, pain or nipple discharge.
- decrease in sex drive that continued after stopping the medication;
- allergic reactions including rash, itching, hives and swelling of the lips, tongue, throat, and face;
- problems with ejaculation that continued after stopping medication;
- testicular pain;
- difficulty in achieving an erection that continued after stopping the medication;
- male infertility and/or poor quality of semen.
in rare cases, male breast cancer.
Tell your healthcare provider if you have any side effect that bothers you or that does not go away.
These are not all the possible side effects of Finasteride. For more information, ask your healthcare provider or pharmacist. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA1088.
How should I store Finasteride?
- Store Finasteride at room temperature between 59˚F to 86˚F (15˚C to 30˚C).
Keep Finasteride in a closed container and keep Finasteride tablets dry (protect from moisture).
Keep Finasteride and all medicines out of the reach of children.
General information about the safe and effective use of Finasteride.
Medicines are sometimes prescribed for purposes other than those listed in this Patient Information. Do not use Finasteride for a condition for which it was not prescribed. Do not give Finasteride to other people, even if they have the same symptoms you have. It may harm them.