Is Pyrilutamide a Safer Alternative to Oral Antiandrogens like Finasteride?

In recent years, the conversation around hair loss treatments has evolved beyond efficacy to a more critical question: safety. Finasteride, a widely used oral antiandrogen, has long been the standard treatment for androgenetic alopecia (AGA), but concerns about its systemic side effects have motivated researchers to look for safer, localized alternatives. Pyrilutamide (KX-826), a topical antiandrogen currently in clinical trials, has been promoted as one such option. Yet, is it genuinely safer, or are we witnessing another premature rush to crown a “miracle” solution?

Understanding the Mechanisms: How These Drugs Work

Finasteride is a 5-alpha-reductase inhibitor, meaning it blocks the enzyme responsible for converting testosterone into dihydrotestosterone (DHT). Elevated DHT levels contribute to miniaturization of hair follicles in individuals genetically predisposed to AGA. When DHT production decreases, hair follicles are less likely to shrink. However, because finasteride works systemically—it circulates throughout the body—it can interfere with hormonal balance beyond the scalp. Pyrilutamide, on the other hand, belongs to a different pharmacological class known as androgen receptor antagonists. Instead of reducing DHT levels, pyrilutamide competes with DHT for binding at the androgen receptor, primarily within the scalp’s hair follicles. In theory, this targeted approach should mitigate systemic hormonal disruptions. Being topical, pyrilutamide is designed to act locally, with minimal absorption into the bloodstream. However, theory and practice are not always perfectly aligned.

What the Evidence Says: Comparing Finasteride and Pyrilutamide

Finasteride has decades of research behind it. Clinical studies and post-marketing surveillance confirm its efficacy in slowing hair loss and promoting regrowth. However, the same body of evidence has also revealed concerning side effects. According to the U.S. Food and Drug Administration’s (FDA) label for Propecia (2012), some patients reported persistent sexual dysfunction even after discontinuing the drug. The UK’s Medicines and Healthcare Products Regulatory Agency (MHRA, 2021) also identified signals linking finasteride to psychiatric symptoms, including depression and suicidal ideation. Although these events are statistically uncommon, their severity has fueled public debate.

Pyrilutamide’s evidence is comparatively sparse and primarily based on early-phase clinical trials. In a 2022 Chinese Phase II trial sponsored by Kintor Pharmaceuticals, **120 men with moderate AGA (Norwood IIIv–V) were treated for 24 weeks with varying concentrations of pyrilutamide. **The group receiving 0.5% twice daily showed an average increase of 22.73 hairs per square centimeter, compared to a 15.34 increase versus placebo (p=0.024). Notably, no serious adverse events were reported, with most side effects being mild scalp irritation. However, this study’s duration—just under six months—does not allow conclusions about long-term safety or systemic absorption.

A U.S.-based Phase II trial (HairScience, 2023) similarly reported that pyrilutamide increased target area hair counts after 24 weeks without major adverse effects. While these findings are promising, it is crucial to note that such data are preliminary and industry-sponsored. Independent, peer-reviewed studies remain limited.

Evaluating Safety: The Complexity Behind “Safer”

Describing one drug as “safer” than another requires context. Finasteride’s systemic activity explains both its therapeutic power and its side effects. Pyrilutamide’s localized mechanism appears advantageous in this regard, but we lack data on chronic exposure, cumulative absorption, and potential hormonal feedback mechanisms. Skin permeability can vary greatly between individuals, meaning some users could still experience systemic absorption. Furthermore, most pyrilutamide studies so far exclude women, individuals with hormonal disorders, or older participants, leaving critical safety questions unanswered. The phrase “no serious adverse events” in early trials should be interpreted cautiously. Many medications show benign short-term safety profiles before revealing problems in post-marketing surveillance. The medical community has seen this before, where the absence of immediate toxicity leads to premature optimism.

Finasteride remains an FDA-approved treatment, supported by robust long-term data on both efficacy and side effects. Pyrilutamide is still investigational, with no FDA approval as of 2025. The regulatory gap underscores the uncertainty: while pyrilutamide shows potential, it is too early to confirm whether it truly offers superior safety. The transition from controlled clinical trials to real-world use often exposes risks that are invisible in small-scale studies. For patients and clinicians alike, the takeaway is not that pyrilutamide is unsafe—but that the claim of being a “safer alternative” cannot yet be substantiated. Science demands time, replication, and transparency, and pyrilutamide is still in that critical early stage.

When asked whether pyrilutamide is a safer alternative to oral antiandrogens like finasteride, the honest answer is: possibly, but not yet proven. The topical nature of pyrilutamide offers theoretical safety advantages, and initial trial data suggest minimal systemic side effects. However, the absence of long-term and independent studies means safety comparisons with finasteride remain speculative. For now, pyrilutamide represents a scientifically promising development that deserves further investigation rather than premature celebration. Until long-term, peer-reviewed evidence emerges, claims of superior safety must be regarded as provisional rather than definitive.

References

Kintor Pharmaceuticals Ltd. (2021, July 11). U.S. FDA greenlights Phase II clinical trial for KX-826 to treat androgenetic alopecia. Retrieved from https://en.kintor.com.cn/news_details/1803365218310795264.html

HairScience. (2023, July 19). Kintor announces update on KX-826 (Pyrilutamide) for hair loss. Retrieved from https://hairscience.org/news/kintor-usa-clinical-trial-pyrilutamide-results/

Perfect Hair Health. (2024, May 9). Pyrilutamide (KX-826) for hair loss: Conflicting study results. Retrieved from https://perfecthairhealth.com/pyrilutamide-kx-826-a-promising-future-treatment-for-hair-loss/

Mysore, V., & Shashikumar, B. M. (2016). Guidelines on the use of finasteride in androgenetic alopecia. Indian Journal of Dermatology, Venereology, and Leprology, 82(2), 128-134. Retrieved from https://ijdvl.com/guidelines-on-the-use-of-finasteride-in-androgenetic-alopecia/

U.S. Food & Drug Administration. (2012). PROPECIA (finasteride) tablets for oral use label. Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2012/020788s020s021s023lbl.pdf]

Medicines and Healthcare Products Regulatory Agency. (2021). Finasteride: reminder of the risk of psychiatric side effects and sexual dysfunction. Retrieved from https://assets.publishing.service.gov.uk/media/6825bc05a4c1a40fde4e63e7/Finasteride_PAR_Accessible_1206.pdf

Seyed Jafari, S. M., Heidemeyer, K., Hunger, R. E., & de Viragh, P. A. (2024). Safety of antiandrogens for the treatment of female androgenetic alopecia with respect to gynecologic malignancies. Journal of Clinical Medicine, 13(11), 3052. Retrieved from https://www.mdpi.com/2077-0383/13/11/3052

Zhong, X., et al. (2025). Multidimensional assessment of adverse events of finasteride: A literature review. PLOS ONE. Retrieved from https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0309849