How Often Do I Need To Apply Topical Finasteride?

How Often Does Topical Finasteride Need To Be Applied?

Most clinicians recommend using topical finasteride at least once daily. However, its minimum viable frequency of application depends on factors such as daily drug exposure and contact time with the scalp.

For those who can keep topical finasteride on their scalps for 10-12 hours (or longer), once-daily applications of low-dose topical finasteride might suffice. For those who can only keep topical finasteride on their scalps for 4-6 hour periods, twice-daily applications may be more helpful – or higher-dose topical finasteride.

After maximum drug saturation has occurred in the scalp (typically after ~30 days of daily applications), it is possible to reduce the frequency of use from once daily to five times weekly – and perhaps even lower – while still seeing hair parameter improvements. However, doing so with low-dose finasteride may come with a reduction in efficacy.

More explanations can be found below.

Finasteride: How Much Is Enough To Regrow Hair?

Clinical studies have demonstrated a steep, dose-dependent, logarithmic response curve for finasteride’s effects on DHT levels. In other words, a little finasteride reduces almost as much DHT as a lot of finasteride. See this chart:

Clinical studies also show that topical formulations of topical finasteride as low as 0.005% x 1 mL, applied twice daily, can improve hair parameters over 16-month periods.^[1]https://www.tandfonline.com/doi/abs/10.3109/09546639709160517

That’s a total daily exposure volume of just 0.1mg daily – or one-tenth that of what is prescribed orally on a daily basis to treat androgenic alopecia (AGA). Needless to say, people with localized hair loss (i.e., just at temples and/or crown) may be able to switch to topical finasteride, reduce their drug exposure, and still see impressive hair growth-promoting effects.

Can Topical Finasteride Be Used Every Other Day?

While usage frequencies lower than once daily haven’t been clinically studied, it’s likely that topical finasteride would still be effective with less frequent dosing schedules.

Why? Because finasteride has a tissue dissociation timing of 4-5 days. In other words, it takes multiple days (and sometimes weeks) for finasteride bound to skin tissue to finally leave that skin tissue and enter the bloodstream, where it is later metabolized and excreted.

Moreover, clinical studies on 1 mg daily of oral finasteride suggest that after one year of use, switching to a 30-days-on, 30-days-off dosing schedule is just as effective as continuing with a once-daily dosing schedule – despite not using the drug for a total of 6 months throughout the same year.^[2]https://jaad.org/retrieve/pii/S0190962220319289

For these reasons, finasteride can still have a therapeutic effect on DHT reduction in the scalp skin, even up to ~30 days after quitting the drug.

This is even reflected in withdrawal studies of oral finasteride, which show that blood levels of DHT can still take multiple weeks to rebound to baseline levels prior to starting the drug.^[3]https://academic.oup.com/jcem/article/89/5/2179/2844345

Richard V. Clark, David J. Hermann, Glenn R. Cunningham, Timothy H. Wilson, Betsy B. Morrill, Stuart Hobbs, Marked Suppression of Dihydrotestosterone in Men with Benign Prostatic Hyperplasia by Dutasteride, a Dual 5α-Reductase Inhibitor, The Journal of Clinical Endocrinology & Metabolism, Volume 89, Issue 5, 1 May 2004, Pages 2179–2184

The same pharmacokinetic relationships also apply to topical finasteride – provided that enough finasteride has saturated the scalp skin to match the levels of exposure in these oral finasteride withdrawal studies.

For a deeper dive into the pharmacokinetics supporting alternate doses and dosing schedules for finasteride, see these articles:

• How Often Should I Take Oral Finasteride?
• How Long Does Finasteride Stay In The Bloodstream?
• How Long Does Finasteride Remain In Scalp Tissues?

What About Scalp Contact Time?

In most cases, the longer a topical sits on the scalp skin, the better chance it has of absorbing into the skin, where it can positively impact hair follicles.

When it comes to topical finasteride, in vitro studies have measured skin absorption rates of the drug over a 24-hour period, and versus different topical formulations – such as finasteride paired with carrier ingredients such as ethosomes, alcohol, liposomes, or water.

The relationships change depending on the finasteride formulation. Just see this chart from the following study:^[4]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2977015/

Penetration profiles of finasteride permeating through human skin from different preparations (mean ± SD, n = 4)

This chart suggests that absorption of topical finasteride is linear across time. In other words, the longer you leave in topical finasteride, the more of it will absorb into your scalp skin – with no diminishing returns over a 24-hour period.

Moreover, these results reveal that across the same time period, those using liposomal finasteride will absorb up to 30% less finasteride into the skin versus those using alcohol-based finasteride – and across the same time period.

This might explain why there are anecdotal reports of fewer side effects while on liposomal finasteride: less of it is getting into the scalp skin, and thereby less of it is leaching into the bloodstream and causing systemic effects. It causes fewer side effects, because it is perhaps less effective.

Additionally, liposomal finasteride users may need to let their topical sit for twice as long on the scalp to reach the same level of absorption as those using alcohol-based finasteride.

To illustrate this, look at the level of absorption for liposomal finasteride at 22 hours. It’s nearly the same as the level of absorption for hydroethanolic finasteride at 10 hours.

Finally, we also have (at least) three other variables at play that will affect finasteride absorption rates, and thereby the frequency at which we should apply topical finasteride on a daily or weekly basis:

1. The total dilution of finasteride (i.e., 0.005%, 0.025%, 0.1%, etc.)
2. The mL per application (i.e., 1 mL for those with localized hair loss, or 2 mL for those with diffuse hair loss)
3. The application frequency (i.e., twice-daily, once-daily, once every-other-day, etc.)

For an example of how important these factors are, just see the results of this 2014 study exploring the effects of once- versus twice-daily dosing of topical finasteride on serum DHT levels:^[5]https://pubmed.ncbi.nlm.nih.gov/25074865

Caserini, M., Radicioni, M., Leuratti, C., Annoni, O., & Palmieri, R. (2014). A novel finasteride 0.25% topical solution for androgenetic alopecia: pharmacokinetics and effects on plasma androgen levels in healthy male volunteers. International journal of clinical pharmacology and therapeutics, 52(10), 842–849.

How Much Topical Finasteride to Apply Daily

If you are opting for daily use of topical finasteride, regardless of the delivery vehicles, here are a few rules-of-thumb to consider:

• Leave for as long as possible on the scalp (If exposure is ≤ 0.1 mg daily and/or if applying less frequently than once daily). This includes a minimum of 10-12 hours, and preferably longer, before washing finasteride out of the scalp skin.
• Stick with 6-12 hour contact windows (if using twice daily)

We hope this article helps! If you’d like personal advice troubleshooting topical finasteride formulations, our research team is happy to support you inside our membership community.