Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 9/19/2019
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 hair loss, a very commonly recommended option for treatment is finasteride (brand name Propecia®). Oral finasteride has been in use since its approval in 1997 by the FDA, but with known sexual side effects like ED and a decreased libido, a switch to topical finasteride could be a preferred alternative.
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 topical finasteride side effects?
We’ll be sorting through answers to that question, but first, let’s explore how topical finasteride works to manage male pattern baldness.
To understand how topical finasteride works, it’s important to have a slight grasp on the formative process of balding in men.
Going a bit technical, baldness is caused by the male hormone dihydrotestosterone (DHT), a major androgen (male sex hormone). The body produces this hormone through the enzyme 5alpha-reductase — this enzyme converts testosterone to DHT.
High DHT levels cause the hair on the scalp to shrink and reduce, leading to baldness. Here’s where finasteride comes in.
Finasteride works as an inhibitor of 5-alpha-reductase. It prevents the conversion of testosterone to dihydrotestosterone, reducing the amount of DHT in the blood, which can prevent further hair loss from baseline.
It can be used by men to treat androgenetic alopecia, and while it shows some promise for managing hair loss in women, it’s important to remember that finasteride is not approved for use by women, and is especially prohibited for pregnant women. This is to reduce any risks of genital defects in male babies.
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.
Now since we mentioned instances of sexual dysfunction linked with its 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.
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.
A study to compare 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.
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 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?
In two studies to determine 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 to compare 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 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, 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, 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.
It offers a better tolerated treatment against hair loss due to its minimal side effects, especially with no links to adverse sexual outcomes.
This 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 you first consult your healthcare provider.
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