Common Topical Finasteride Side Effects
Reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Once you hit the age of 50, several things, both good and bad, happen. You’re eligible to sign up for AARP, you can use the excuse “I’m too old” to get out of things and there’s a good chance you’ll be experiencing some degree of hair loss.
The most common form of hair loss, male pattern baldness (also called androgenetic alopecia or AGA) affects up to 50 percent of men by age 50. Welcome to the club!
Fortunately, there are ways to treat male pattern baldness. The oral medication finasteride (brand name Propecia®) is a common recommendation and is one of two FDA-approved medications for the treatment of androgenetic alopecia.
But oral finasteride has known sexual side effects like decreased libido and erectile dysfunction from the oral tablet, so using a topical finasteride treatment could be a preferable alternative for some people.
However, topical finasteride has yet to receive FDA approval and there’s very limited research on its benefits or even how it works. That all leads to some pressing questions that need to be answered: Does topical finasteride have side effects? And perhaps more importantly, is topical finasteride safe?
Side Effects of Topical Finasteride
Before we look into topical finasteride side effects, let’s first look at how topical finasteride works to manage male pattern baldness.
The receding hairline or thinning hair that signals hair loss is caused by enzymes that convert testosterone into the male sex hormone dihydrotestosterone (DHT), a major androgen.
High DHT levels cause the hair follicles — the tiny organs throughout your scalp from which your hair grows — to shrink, leading to baldness.
Finasteride belongs to a group of medications called 5-alpha reductase inhibitors. These medications prevent the conversion of testosterone to dihydrotestosterone, which can prevent further hair loss.
But while oral finasteride takes effect through systemic absorption (absorption by every part of the body — skin, hair, liver, etc.), the topical formulation provides localized treatment, just on your scalp.
Every medication can have potential side effects. If you’ve ever looked up finasteride side effects, you may have seen common adverse effects like sexual dysfunction, reduced ejaculation or even insomnia from finasteride. However, these are most often from oral finasteride.
But is topical finasteride safe and effective? Does it have different side effects? There’s a little bit of research that has looked at these questions.
A clinical study that compared the effects of oral finasteride against a finasteride 0.25% topical solution was carried out on 24 men with androgenetic alopecia.
The men who applied the topical finasteride solution to their scalps for one week showed similar results to those who took 1mg of oral finasteride for the same amount of time. Specifically, scalp DHT was reduced by 68 to 75 percent when topical finasteride was used, compared to 62 to 72 percent with the oral tablet. Researchers also found that the topical solution was well-tolerated.
Another study in the Indian Journal of Dermatology comparing the effects of topical finasteride gel to the oral tablet form was carried out on 45 men with androgenetic alopecia. The patients used the gel twice a day for six months, while the finasteride tablets were used once a day.
By the end of the study, both groups saw similar positive effects on hair growth.
Finally, a study of more than 440 patients that looked at the effectiveness of a topical finasteride spray compared to the oral tablet found that the spray significantly improved hair count compared to placebo, but had less of an impact on serum DHT levels than the oral version.
While all these studies show promising results for the effectiveness of topical finasteride, many are too small to gauge if a finasteride spray would really encourage hair regrowth.
But what about topical finasteride spray side effects or adverse effects of a finasteride gel?
Topical finasteride, like all medications, can lead to some side effects. But many of these studies reported that the hair loss treatment was well-tolerated, with a few minor side effects, including:
Redness at application site
Although much rarer, serious side effects are possible. For example, two subjects in the first study reported increased levels of alanine transaminase — a dangerous situation for the liver with high, frequent daytime urination and testicular pain.
And while we can all appreciate a moment of craftiness, we have to urge that you don't make your own topical finasteride.
Hims has helped thousands of men regrow their hair
Is Topical Finasteride Safe to Use with Other Hair Loss Products?
Maybe you’re so frustrated with your hair loss and you want to double down on treatment efforts by combining topical finasteride with another hair loss product. But is topical finasteride safe when used with other hair loss treatments?
Besides oral finasteride, the other medication that’s approved by the FDA for male pattern hair loss is minoxidil.
Minoxidil, a topical solution, stimulates hair growth by encouraging blood flow to your hair follicles. It’s also thought that minoxidil lengthens the growth phase of your natural hair growth cycle.
In a study to test the effectiveness of a treatment that combined topical finasteride, dutasteride (another 5-alpha reductase inhibitor) and topical minoxidil, 15 male patients applied a mix of these products for nine months.
Those who used the topical finasteride treatment, dutasteride and minoxidil solution saw hair growth after three months. This combination was well-tolerated, even in patients with a tendency for allergies.
If you’re looking for a combination solution to treat hair loss, we offer a topical finasteride & minoxidil spray.
If you’re looking for more ways to encourage hair growth or boost thin hair, adding supplements like biotin gummies can lead to a fuller head of hair.
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No matter the treatment plan, the best place to start is somewhere. Early action is the best hair loss prevention.
Topical Finasteride Side Effects: Takeaways
While FDA-approved to treat male hair loss, oral finasteride can cause side effects like sexual dysfunction. Therefore, some may opt for a topical finasteride treatment option to reduce the risk of those systemic side effects.
But is topical finasteride safe, and what side effects can you expect? Here’s what you need to know.
Finasteride works to block the conversion of testosterone into the hormone dihydrotestosterone (DHT), which causes male pattern baldness. While often prescribed as an oral tablet, topical finasteride solutions are available (but not FDA-approved).
While there haven’t been any large studies of the effects of topical finasteride, multiple smaller studies have shown that it significantly improved hair count and hair density, with lower risk of side effects.
There can be some side effects of topical finasteride though, such as irritation, an itching or burning sensation, lightheadedness or redness where the solution is applied.
You can learn more about topical finasteride use, from how to apply it to safety measures, in our full guide. We’ve also covered the effectiveness of topical finasteride and gone more in-depth on the side effects of oral finasteride.