Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 4/15/2022
If you’re about 50, with a thinning hairline or declining hair mass, you’re in good company. Male pattern baldness or androgenetic alopecia is the most common form of hair loss, affecting about 30 percent to 50 percent of men by age fifty.
To manage male pattern hair loss, a very commonly recommended option for treatment is the oral medication, finasteride (brand name Propecia®). Oral finasteride has been in use since its approval in 1997 by the FDA, according to the book, StatPearls, but with known sexual side effects like ED and a decreased libido, a switch to topical finasteride could be a preferred alternative for your hair follicles, according to an article published in the Indian Dermatology Online Journal.
However, with topical finasteride yet to receive FDA approval, coupled with very limited research on its benefits, or how it works, a pressing question begs to be answered: what are the common side effects of topical finasteride?
We’ll be sorting through answers to that question, but first, let’s explore how topical finasteride works to manage male pattern baldness.
According to an article published in the journal, Plastic and Reconstructive Surgery, baldness is caused by the male hormone dihydrotestosterone (DHT), a major androgen (male sex hormone). High DHT levels cause the hair on the scalp to shrink and reduce, leading to baldness.
Finasteride works as an inhibitor of 5-alpha-reductase by preventing the conversion of testosterone to dihydrotestosterone, which can prevent further hair loss from baseline.
However, while oral finasteride takes effect through systemic absorption i.e absorption by every part of the body — skin, hair, liver etc — the topical formulation provides localized treatment, having decreased absorption when compared to the oral form.
You may be thinking, does topical finasteride have side effects? Let’s find out.
If you’ve ever googled finasteride side effects, or, more likely — checked out finasteride side effects on reddit, you’d notice that commonly named adverse effects of finasteride include low libido, erectile dysfunction, reduced ejaculatory volume, and gynecomastia, according to an article published in the book, StatPearls.
These effects have been observed following the systemic absorption of oral finasteride, and may place the safety of this drug under question.
Topical finasteride has been positioned as a better tolerated, less severe alternative to its oral equivalent with systemic side effects.
TL;DR – a few different studies have reported minimal side effects of topical finasteride, including lightheadedness, conjunctivitis, headaches and oropharyngeal pain.
A study published in the International Journal of Clinical Pharmacology and Therapeutics that compared the effects of topical against oral finasteride was carried out on 24 men with androgenetic alopecia.
The men that applied 1ml of a topical finasteride solution to their scalps for one week showed similar results to those who took 1mg of oral finasteride for 7 days.
Scalp DHT was reduced by 68 percent to 75 percent when topical finasteride was used, compared to 62 percent to 72 percent with the oral tablet. Topical treatment finasteride was also absorbed at around 10-15 times lower than the tablet.
But while the adverse effects associated with oral finasteride may be absent, what can be expected following topical finasteride use?
The same study published in the International Journal of Clinical Pharmacology and Therapeutics determined the effects of topical finasteride on DHT levels in hair loss, men between the ages of 18-65 with androgenetic alopecia were given topical solution finasteride at a 0.25% dosage.
In the first study, 18 subjects were divided into three groups and given the topical solution once daily, twice daily, or the finasteride oral tablet for one week.
The second study had 32 patients, where 8 received the topical solution for seven days.
Participants in the first study who were given the topical solution reported lower DHT levels when compared to the oral tablet. The second study also recorded similar effects.
However, while the topical solution was well tolerated in both groups, in the first study, two subjects reported increased levels of alanine transaminase — a dangerous situation for the liver when high, frequent daytime urination and testicular pain.
The second group also had complaints of lightheadedness, conjunctivitis, headaches and oropharyngeal pain from the topical solution.
Another study published by the Mazandaran University of Medical Sciences comparing the effects of topical finasteride gel against its tablet form was carried out on 45 men with androgenetic alopecia. The patients were to use 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 had similar positive effects on hair growth. However, while one user of the finasteride tablet complained of a reduced libido, one complaint of reddening skin was made in the finasteride gel group.
More research is however needed to understand the full effects of topical finasteride.
On its own, we’ve observed topical finasteride to be a well-tolerated, largely safe for use medication, this is also the case when combined with other treatments for hair loss.
In a study published in the journal, International Scholarly Research Notices, to test the effectiveness of a treatment that combined topical finasteride, dutasteride and minoxidil, 15 male patients were to apply a mix of these products for 9 months.
These subjects also had the option to include 1mg of oral finasteride daily, topical minoxidil foam at least once per day, or topical ketoconazole 2% shampoo to their routine.
Eight chose the four treatment option route and saw significant hair growth within just 30 days.
However, those that used only topical finasteride treatment, dutasteride and minoxidil saw growth after three months, taking special notice of the safety of the combination. It was well tolerated and effective, even in patients with a tendency for allergies.
In another study published by the Medical Association of Thailand, this time for 24-weeks, the effectiveness of minoxidil alone over a minoxidil-finasteride lotion mix was put to the test. Forty men with androgenetic alopecia were selected then divided into a minoxidil-only group, or a minoxidil-finasteride group for evaluation.
At the end of the study, the minoxidil-finasteride combination produced better results in a photographic assessment, despite having similar hair count results with minoxidil alone.
The topical formulation proved to be a safe and effective hair loss treatment, with no sexual side effects.
Topical finasteride provides an alternate formulation to the original oral alpha-reductase inhibitors for the treatment of androgenetic alopecia.
Although it’s not FDA approved, topical finasteride may offer a better tolerated treatment against hair loss due to its minimal side effects, especially with no links to adverse sexual outcomes. While there have been some small, beneficial studies with evidence to support this, more research is needed over time.
This hair regrowth treatment may also provide a safe, fortified remedy against hair loss in conjunction with other hair loss products.
Topical finasteride may be found in gels, foam or liquid solutions. Before deciding on this therapy for hair loss, make sure to first seek medical advice from your healthcare provider.