Medical Review by Jennie Stanford, MD, FAAFP, DABOM
Summary:
- Finasteride is a 5α-reductase inhibitor used to treat male hair loss and certain prostate conditions by preventing the conversion of testosterone into dihydrotestosterone (DHT).
- This reduction in DHT that helps slow hair loss may temporarily increase testosterone levels in the blood by 15-25%.
- Increased testosterone from finasteride may offer benefits like lower body fat and improved bone mineral density but can raise the risks of prostate cancer, hypertension, and spinal stenosis.
- Common finasteride side effects include loss of libido, erectile dysfunction, decreased ejaculatory volume, and gynecomastia. More serious effects might include allergic reactions and post-finasteride syndrome—although these are rare.
- Consulting with a healthcare provider is essential for managing risks and determining if finasteride is appropriate, especially for individuals with conditions like depression or sexual dysfunction.
Learn whether taking finasteride impacts your testosterone levels
Finasteride is an FDA-approved medication that treats hair loss in men, along with certain prostate conditions. It belongs to a class of medications called 5α-reductase inhibitors (5-ARIs), which reduce your body’s ability to convert testosterone into dihydrotestosterone (DHT)—a hormone linked to prostate enlargement and hair loss.
But testosterone plays several important roles in the body, so it’s natural to be curious about what other effects finasteride could have. Below, we teach you more about the relationship between finasteride and testosterone. Use what you learn here to have an informed conversation with your healthcare provider about the potential benefits and risks associated with finasteride use.
How finasteride works
The specific type of hair loss that finasteride is approved to treat is called androgenic alopecia. This genetic condition affects approximately half of all people worldwide, and is associated with higher levels of DHT.
How androgenetic alopecia causes hair loss
When you have androgenetic alopecia, several things happen:
- Specific receptors in your scalp called androgen receptors become activated.
- This affects your hair growth cycle by shortening the growth phase of nearby hair follicles.
- As a result, hair becomes thinner and shorter—and in some cases, unable to grow through the skin on your head.
How 5-ARIs like finasteride help
5α-reductase is an isoenzyme responsible for converting testosterone into DHT. There are three different types of 5α-reductase: type 1, type 2, and type 3.
Finasteride works on Type 2, which affects your hair follicles and is responsible for over two-thirds of the DHT in your bloodstream. Here’s how:
- Finasteride slows down the production of 5α-reductase type 2.
- This helps prevent testosterone from being converted into DHT.
- As a result, there is less DHT to activate the androgen receptors in your scalp that affect your hair growth.
The relationship between finasteride & testosterone
Since finasteride prevents testosterone from being converted into DHT, it temporarily increases the amount of testosterone circulating in your blood. Research suggests that your testosterone levels could temporarily increase by 15-25%.
Potential benefits of higher testosterone
Some research suggests that boosting your testosterone levels might have benefits. These could include:
- Lower body fat percentage
- Improved mineral density for certain bones
- Possible anti-inflammatory effects via lowering certain protein levels
Potential drawbacks of higher testosterone
But raising testosterone levels might also have negative effects. These might include increased risks of:
- Prostate cancer
- Spinal stenosis (a narrowing of the spinal canal that can put pressure on the spinal cord and nerve roots)
- Hypertension (high blood pressure)
Contrary to some popular beliefs, increasing your testosterone levels has not been shown to have any major benefits for cardiovascular health, cognitive function, or preventing diabetes.
Testosterone conversion to estrogen
It’s also important to note that testosterone circulating in your bloodstream can be converted into estrogen, while DHT cannot convert to estrogen. If you are taking finasteride, this could eventually shift your hormone balance and cause you to have higher than usual levels of estrogen, although this phenomenon is more common in older males.
Side effects and risks of finasteride
DHT also plays an important role in male sexual development. So while taking finasteride might prevent or reduce hair loss by lowering DHT levels, changing the balance of your hormones can also come with the risk of certain side effects.
Common sexual side effects
Some of the most common sexual side effects associated with finasteride include:
- Loss of libido: You might experience less interest in sexual activities.
- Erectile dysfunction: 2-4% of people taking finasteride experience difficulty achieving or maintaining an erection.
- Decreased ejaculatory volume: You might release less semen when you ejaculate.
- Gynecomastia: Some people who take finasteride also develop enlarged breast tissue. Contact your healthcare provider if you notice lumps, pain, discharge, or an increase in the size of your breasts.
Sometimes, sexual side effects can also come with psychological consequences—including depression and suicidal thoughts. If you are having thoughts of suicide, contact a qualified medical practitioner right away or call a crisis line to speak with someone who can help.
Find Help for Depression Online
Rare but serious side effects
Finasteride can also have more serious side effects. These might include:
- Severe allergic reactions: Contact your healthcare provider as soon as possible if you experience a rash, itching, hives, swelling in your lips or face, or trouble breathing or swallowing.
- Post-finasteride syndrome: Some people have reported unwanted effects that lasted for at least three months after they stopped taking finasteride. This has been called post-finasteride syndrome—but there is still debate in the medical community about whether it actually exists since many of the patients who reported it also had other disorders.
Managing your side effects
Because finasteride affects your hormone levels, it’s important to talk with your healthcare provider about any other conditions you have that could also be affected by these changes. Specifically, your provider may ask you whether you have a history of the following conditions before prescribing finasteride to you:
- Depression
- Sexual dysfunction
- Infertility
Having one or more of these conditions does not necessarily mean finasteride won’t be prescribed to you. But if your healthcare provider thinks these conditions could be made worse by taking finasteride, they may suggest alternative hair loss treatments or monitor your finasteride use more closely.
When taking finasteride, monitoring and regular check-ups with your healthcare provider are important, even if you don’t have any of the conditions listed above. You should also contact your healthcare provider as soon as possible if you notice any adverse effects when taking finasteride.
Find expert support to help you make informed choices about finasteride
Use the information above to help guide your conversations with healthcare providers and make more informed decisions about finasteride with their help. Only a qualified medical professional can prescribe finasteride to you, adjust your dosage if necessary, and monitor your safety to address side effects if they occur during use.
Lemonaid Health can help by putting you in touch with US-based medical professionals who can answer your questions about finasteride during private online consultations. We can help you learn more about how finasteride might affect you—including how you might benefit from it and what specific risks you might face.
We can also prescribe appropriate FDA-approved hair loss medication in clinically indicated cases, and arrange for your medication to be delivered to your doorstep. Find effective support for hair loss with our help.
