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 behaviour?
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 body, and the options that are available for limiting the negative effects of DHT on your hairline.
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 ‘ miniaturisation,’ 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, one of the most effective ways 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 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, 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 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.
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.
On average, a daily dose of 1mg finasteride blocks DHT production enough to stop most hair loss. In certain cases, it can also cause miniaturised hair follicles damaged by DHT to start to grow back.
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:
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 very rare for any negative symptoms to persist if you don’t actively take a DHT blocker.
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.