Topical or oral? Choosing between pills and lotions according to your case.

Traditionally. Finasteride is taken orally (1 mg daily) to halt hair loss and promote regrowth. Recently, topical formulations of finasteride have gained attention as a potentially equally effective treatment with fewer systemic side effects. This report provides a comprehensive review of the efficacy and differences between topical and oral finasteride, drawing on clinical studies (human trials), mechanistic research (including animal studies), meta-analyses, and reported outcomes. We examine how each route affects hair growth, DHT levels, pharmacokinetics, dosing, and side effects.

Mechanism of Action and Evidence from Research: Finasteride’s Mechanism:

Finasteride selectively inhibits 5α-reductase type II (and to a lesser extent type I), the enzyme that converts testosterone to DHT. In androgenetic alopecia, hair follicles in the scalp miniaturize under the influence of DHT. By lowering DHT, finasteride helps prevent follicular miniaturization and can restore healthier hair growth. Mechanistically, oral and topical finasteride work the same way at the hair follicle level – the difference is in drug delivery (systemic vs localized). Topical application is intended to concentrate the drug in the scalp to reduce local DHT production with less systemic absorption.

Human Mechanistic Studies: Key pharmacologic studies in humans have compared how topical vs oral finasteride affect hormone levels. In a 2014 study (Caserini et al.), healthy men were given either finasteride 0.25% topical solution or 1 mg oral finasteride daily for one week. Both routes resulted in significant DHT suppression. In fact, scalp DHT levels decreased by about 70% from baseline with topical finasteride, which was comparable to the ~60–70% reduction seen with oral finasteride. Plasma DHT was likewise suppressed ~68–75% by the topical solution vs ~62–72% by oral finasteride after one week, with no relevant changes in plasma testosterone in either group. The absence of a compensatory rise in testosterone with topical finasteride (which is usually observed with oral finasteride due to reduced T→DHT conversion) suggests the systemic exposure was lower.Overall, mechanistic studies (in humans and animals) support that finasteride’s hair-growth effect comes from DHT blockade, and that topical application can achieve this locally while lessening systemic exposure.

Efficacy of Oral Finasteride (Clinical Studies)

Oral finasteride (1 mg daily) is a well-established treatment for male androgenetic alopecia. Multiple large randomized controlled trials (RCTs) and long-term studies have confirmed its efficacy. In these trials, oral finasteride consistently increases hair counts and slows hair loss compared to placebo. For example, men taking 1 mg finasteride daily experienced progressive increases in hair count at 6, 12, and 24 months, whereas placebo-treated men continued to lose hair.

A network meta-analysis of treatments found that at 48 weeks, oral finasteride 1 mg/day yielded one of the greatest increases in total hair count among all hair loss therapies tested. Clinically, about 80–90% of men show no further hair loss or some regrowth on oral finasteride over 1–2 years. In one 2-year study, 83% of men on finasteride had no progression of hair loss (or improvement) versus 28% of men on placebo. These results underline that oral finasteride is highly effective at stabilizing male pattern hair loss and often leads to visible regrowth, especially in the crown area. Moreover, efficacy persists with continued use: 5-year extension studies show sustained or increased hair counts in those who stay on the medication, whereas those who stop tend to regress and lose hair again, reflecting DHT’s ongoing role in hair follicle miniaturization.

Note: Oral finasteride is also used off-label in women with androgenetic alopecia, typically at lower doses (e.g. 0.25–1 mg) especially in post-menopausal women. While this review focuses on male AGA, many findings apply broadly. Women of childbearing potential generally avoid systemic finasteride due to risk of male fetal development abnormalities, which is one reason topical finasteride is being explored in women as well.)

Efficacy of Topical Finasteride:

Early Trials:

The first human study on topical finasteride was published in 1997 by Mazzarella. In that single-blind placebo-controlled trial, 52 patients (28 men, 24 women) applied a 0.005% finasteride solution daily for 16 months. The low-strength topical finasteride still produced improvements: it slowed hair loss and modestly increased hair growth compared to placebo, demonstrating proof-of-concept that even a small amount of finasteride delivered to the scalp can impact androgenetic alopecia.

By the end of the study, the finasteride group showed a reduction in balding progression, whereas the placebo group had continued hair thinning, but it established topical finasteride’s potential.

Several other studies have evaluated topical finasteride, often in combination with minoxidil: A 2020 trial by Rossi found that a combo of 0.25% finasteride + 5% minoxidil solution outperformed minoxidil alone in promoting hair growth. Only the combination (minoxidil + finasteride) yielded a statistically significant increase in hair density at 6 months, whereas minoxidil by itself did not show a significant change. Another study from 2021, assessed patient-reported outcomes in men using either topical finasteride with minoxidil vs oral finasteride with minoxidil.

Both approaches were effective and well-tolerated, with no patient-observed superiority of one over the other. In general, every controlled study of topical finasteride to date has reported positive outcomes-

Effects on Serum DHT:

Lower systemic absorption translates to a smaller impact on serum (circulating) DHT levels for topical finasteride. Oral finasteride 1 mg typically reduces serum DHT by ~60–70% on average with daily use. Topical finasteride, in contrast, tends to cause a more modest serum DHT reduction, although still significant. In the 2021 topical finasteride trial, mean serum DHT dropped about 34.5% from baseline in the topical group, compared to about 55.6% reduction typically expected with oral finasteride. Other studies have similarly noted that topical finasteride lowers serum DHT less than oral finasteride does. This is a desirable feature if one’s goal is to avoid systemic hormonal changes.

However, it’s noteworthy that some topical regimens (especially higher doses) can still suppress DHT considerably. Caserini et al. found that after one week of 0.25% topical finasteride (applied twice daily), plasma DHT was reduced by ~70%, which was essentially the same DHT suppression achieved by oral finasteride in that short-term comparison.This implies that sufficiently dosed topical finasteride can mimic oral finasteride’s hormonal effect at least transiently. In practice, most topical protocols aim for a balance: enough absorption to impact scalp DHT (and some systemic DHT) but not so much as to saturate the system.

Dosage Equivalence:

A common question is how the dosage of topical finasteride compares to the oral version. Although not an exact equivalence, it is estimated that 1 mL of a 1% topical solution could be similar to 1 mg of oral finasteride in terms of DHT suppression. For example, one analysis suggests that 1 mL of a 1% solution (containing 10 mg of finasteride, although only a fraction is absorbed) reduces blood DHT by approximately 71%, a level comparable to the 70% achieved with oral finasteride. On the scalp, absorption of topical finasteride is 10-15%, achieving a reduction in blood DHT of close to 50%, in addition to good results in hair growth. Because of this, a 0.25% topical solution applied once daily is considered to be approximately equivalent to 1 mg daily of oral finasteride, which is supported by many specialists.

Dactors affecting topical dosage: Unlike the pill, which has a fixed dosage, topical finasteride application can vary by patient. Factors such as the amount applied and how it is spread over the scalp can influence its effectiveness. Also, if an application is missed, its impact on efficacy is more immediate than with the oral version, as there is no systemic “depot” of the drug in the body.

Anecdotal Reports from the Community

Beyond formal studies and case reports, a wealth of anecdotal information exists in online communities. One such community is Reddit’s r/tressless, the largest hair loss forum, where thousands of individuals share experiences with treatments like finasteride. These anecdotal reports are not scientific data, but they provide insights into real-world usage and perceptions of topical vs oral finasteride. Below, we summarize common themes from the Tressless community, clearly marking them as anecdotal (community experiences rather than verified research). Keep in mind individual experiences vary widely, and anecdotal reports may be subject to placebo effects, nocebo effects, and personal bias.

*Effectiveness Perceptions: Many users on Tressless who have tried topical finasteride report positive results in terms of halting hair loss and regrowth, similar to their experiences (or others’ experiences) with oral finasteride. It’s commonly stated that topical finasteride “works” for maintaining hair. For example, one user emphatically noted they had “experienced absolutely 0 side effects, not even topical ones, and am extremely happy” with their results on topical finasteride

Side Effect Comparisons:** A frequent discussion topic is whether topical finasteride truly has fewer side effects than oral. The general community consensus is that topical has a lower risk, but not zero. Many report no sexual side effects on topical, even some who had issues on oral. However, others caution that topical finasteride can still cause systemic absorption. One commenter pointed out that topical finasteride’s systemic absorption is proven to be lower than oral, but “even the reduced absorption can cause side effects” for very sensitive individuals.

Reports of Side Effects on Topical: While most seem to tolerate topical well, a few anecdotal posts describe side effects. These range from mild sexual symptoms to severe. On the extreme end, at least one user claimed to develop “full blown post-finasteride syndrome” from using topical finasteride. This individual took 0.1% topical finasteride for only 10 days and reported lasting sexual dysfunction and other issues (an anecdote that mirrors the controversial PFS cases with oral).

Such reports are rare but serve as reminders that a small minority might react adversely even to topical application. Other users have mentioned experiencing shedding or irritation with topical, or subtle decreases in libido that resolved after discontinuation (all self-reported, without medical confirmation). For balance, it’s worth noting that countless other users report no noticeable side effects on topical finasteride, reinforcing that these cases are exceptions.

Switching from Oral to Topical: A common scenario discussed is men switching to topical finasteride after experiencing side effects on oral finasteride. Many of these users report that their side effects (for example, erectile dysfunction or low libido) went away after switching to topical, yet their hair maintenance continued. This suggests that for some, the difference in systemic exposure is enough to alleviate adverse effects while keeping DHT low in the scalp. However, not everyone’s experience is positive – a few report that even on topical, they still had milder versions of the same side effects, or that their hair results were not quite as good as on oral. Personal physiology seems to play a big role.

Community Attitudes: On Tressless, there’s a mix of attitudes. Some members are very pro-topical, calling it “the perfect hair treatment no one talks about,” and wondering why more people don’t start with topical given its *“little to no side effects in comparison”. Others are more skeptical, feeling that oral is easier and the side effect difference might be overstated. There are also practical discussions about cost (topical finasteride is not mass-market in some countries and often must be compounded, which can be more expensive than generic finasteride pills). Convenience is another factor – taking a pill vs applying a topical solution daily (which can leave residue or be time-consuming). Some users find the topical routine easy, while others dislike it.

Note: Community reports are anecdotal and not rigorously verified; they should not replace clinical evidence, but rather illustrate how findings might translate to everyday use. Always consult a healthcare professional for personal medical advice.

Conclusion

Both topical and oral finasteride are effective treatments for androgenetic alopecia, achieving similar outcomes in terms of reducing hair loss and promoting regrowth. Oral finasteride has the advantage of convenience and a long track record of efficacy, but at the cost of systemic DHT suppression that can lead to side effects in a subset of users. Topical finasteride, on the other hand, represents a refined approach: by localizing the drug’s activity to the scalp, it minimizes systemic exposure and thereby tends to reduce the incidence of side effects, all while maintaining robust efficacy in the target area.

However, it’s important to keep expectations realistic. Topical finasteride is not entirely without risk, and oral finasteride is not intolerable for everyone – in fact, most oral users have no major issues. The choice between topical and oral may come down to individual preference, tolerability, cost, and access. Some may start with oral finasteride and switch to topical if needed; others might prefer to try topical first.  From a physician’s perspective, topical finasteride expands the toolkit for treating hair loss. It can be especially useful in patients who are hesitant about oral medication or who have contraindications (for example, men who are trying to conceive might prefer to avoid systemic drug exposure, though evidence on finasteride’s effect on fertility is mixed). Also, in women of childbearing age with alopecia, topical finasteride (often combined with minoxidil) is sometimes used cautiously off-label under strict avoidance of pregnancy.

Sources:

A novel finasteride 0.25% topical solution for androgenetic alopecia. (n.d.). PubMed. https://pubmed.ncbi.nlm.nih.gov/25074865/

Finasteride and dutasteride for the treatment of male androgenetic alopecia: A review of efficacy and reproductive adverse effects. (n.d.). GMR Scholastica. https://gmr.scholasticahq.com/article/88531

Hair growth effects of oral administration of finasteride. (n.d.). PubMed. https://pubmed.ncbi.nlm.nih.gov/1309834/

Maculopapular drug eruption caused by finasteride: A case report. (n.d.). National Center for Biotechnology Information (NCBI). https://pmc.ncbi.nlm.nih.gov/articles/PMC10661891/

Male pattern hair loss: Prevention rather than regrowth. (2000). Wiley Online Library. https://onlinelibrary.wiley.com/doi/10.1046/

Topical finasteride for hair loss: How well does it work? (n.d.). Healthline. https://www.healthline.com/health-news/topical-finasteride-for-hair-loss-how-well-does-it-work

Topical finasteride for male and female pattern hair loss: Is it safe? (n.d.). Wiley Online Library. https://onlinelibrary.wiley.com/doi/10.1111/jocd.14895?af=R/1000#

Topical finasteride: To use or not to use? (n.d.). International Society of Hair Restoration Surgery (ISHRS). https://www.ishrs-htforum.org/content/28/3/112