RU58841: Is it safe or does it have strange side effects?

What is RU58841, and why is it gaining attention?

RU58841 is a non-steroidal anti-androgen (NSAA), originally developed as a potential treatment for conditions like androgenic alopecia (male and female pattern hair loss) and even acne. Unlike widely-known medications such as finasteride, which work systemically by inhibiting the enzyme 5-alpha reductase to reduce dihydrotestosterone (DHT) levels throughout the body, RU58841 functions more directly at the source of the problem.

It binds specifically to androgen receptors in the scalp, blocking DHT locally without significantly affecting overall hormone levels. This makes it particularly appealing to those seeking to avoid the systemic side effects associated with oral treatments, such as sexual dysfunction, mood disturbances, or hormonal imbalances.

The prospect of a treatment that targets hair loss without impacting the rest of the body is understandably enticing — but is this promise backed by science, or does RU58841 carry hidden risks that haven’t been fully explored yet?

Who makes RU58841?:  Brands and laboratories producing it

Since RU58841 is not an officially approved pharmaceutical product, it’s not manufactured by major, regulated pharmaceutical companies.

Instead, it’s primarily sold by research chemical suppliers. Some of the more well-known names in the market include:

Kane Research: Kane Research Chemicals, based in the United States, specializes in providing experimental compounds for scientific study, though they remain unregulated for personal use.

Chemyo: also US-based, markets itself as a high-purity supplier, often showcasing third-party lab tests to support its product quality claims.

Anagen Inc.: originating from Canada, focuses on research chemicals related to hair loss and dermatological studies, though, like the others, it operates without official pharmaceutical oversight.

Note: These companies market RU58841 for “research purposes only,” which is a legal loophole allowing the sale of experimental compounds not approved for human use.

The challenge is quality control.

Unlike FDA-approved medications, RU58841 from these suppliers isn’t subject to the same rigorous manufacturing and safety standards. This means purity, concentration, and formulation can vary between sources — a factor that may influence both effectiveness and the risk of side effects. Some suppliers provide Certificates of Analysis (COAs) from third-party labs to verify purity, but not all do, leaving buyers to navigate an unregulated marketplace.

How is RU58841 used? Topical vs. oral application

RU58841 is most commonly applied topically — directly to the scalp. This method aligns with its intended mechanism: blocking DHT locally without affecting systemic hormone levels. Users typically dissolve the compound in a carrier solution like propylene glycol or ethanol, applying it to areas affected by hair loss once daily. This approach aims to maximize scalp penetration while minimizing systemic absorption.

Oral use, on the other hand, is almost unheard of — and for good reason. RU58841 was designed as a localized treatment. Taking it orally would likely increase systemic exposure, potentially leading to more pronounced hormonal side effects throughout the body, similar to oral anti-androgens like bicalutamide, which are used in prostate cancer treatment. There’s no research supporting oral consumption of RU58841 for hair loss, and doing so would introduce unknown risks.

Ultimately, topical application remains the method that aligns with both research and user reports — though even this route lacks long-term safety data.

RU58841 is a non-steroidal anti-androgen (NSAA), originally developed as a potential treatment for conditions like androgenic alopecia (male and female pattern hair loss) and even acne.

Unlike widely-known medications such as finasteride, which work systemically by inhibiting the enzyme 5-alpha reductase to reduce dihydrotestosterone (DHT) levels throughout the body, RU58841 functions more directly at the source of the problem.

It binds specifically to androgen receptors in the scalp, blocking DHT locally without significantly affecting overall hormone levels. This makes it particularly appealing to those seeking to avoid the systemic side effects associated with oral treatments, such as sexual dysfunction, mood disturbances, or hormonal imbalances.

The safety debate: Promising potential or uncharted territory?

When it comes to RU58841, the question of safety isn't just about whether it works — it’s about what’s happening beneath the surface, literally. The compound’s ability to block DHT directly at the scalp without affecting the rest of the body sounds ideal, but without robust human trials, we’re left navigating a gray area filled with partial answers and speculation.

Fast-forward to 1998, and we find a more promising study on macaques, a species with skin and hair growth patterns closer to ours. Over six months, these macaques showed visible hair regrowth without notable changes in their systemic hormone levels. It’s a hopeful sign, yet the small sample size and relatively short duration leave us wondering what happens beyond those six months.

A 2004 study dove deeper into the absorption question, using rats to measure how much of the compound enters the bloodstream. While most of RU58841 stayed localized to the scalp, trace amounts still made their way into the system. This raises an uncomfortable question: could prolonged use lead to gradual systemic effects? Without longer, human-specific trials, that’s a door left wide open.

What makes things more complex is the scattered, anecdotal evidence from users experimenting on themselves. Forums and online communities are filled with mixed reports — some claim life-changing regrowth, while others mention fatigue, mental fog, or even hormonal changes. The issue? These reports lack the structure of controlled studies, making it impossible to separate legitimate side effects from coincidence or improper formulation.

RU58841 stands on a tightrope between exciting potential and unknown consequences. It’s not just a matter of whether it works — it’s about whether it works safely in the long term. Without larger-scale human studies, that answer remains frustratingly out of reach.

User Experience

Many users acknowledge RU58841’s effectiveness in blocking DHT at the scalp level, leading to visible hair regrowth. However, safety remains a major concern due to the lack of long-term clinical studies. One user shared a troubling experience of severe side effects, including heart palpitations and shortness of breath, prompting them to stop using RU58841 entirely. Others mention the risk of systemic absorption — meaning the drug could circulate beyond the scalp — with users recommending applying it at night or using lower concentrations to mitigate this risk. Some suggest avoiding microneedling alongside RU58841 to prevent deeper penetration into the bloodstream.

Another frequent topic is the DIY nature of RU58841. Many users debate whether to purchase pre-made solutions or mix their own using powder, ethanol, and propylene glycol. While DIY methods are cheaper, some users report inconsistency in results and worries about contamination or incorrect dosages. In contrast, premixed solutions, though more expensive, provide more reliability.

Side effect management strategies are widely discussed. Some users recommend grapefruit juice, which may slow liver metabolism of certain substances, potentially reducing systemic side effects. There’s also talk of cycling on and off RU58841 to give the body a break, though no scientific evidence supports this.

In contrast to those reporting side effects, other users claim they’ve experienced no adverse effects, even after prolonged use. A few mention combining RU58841 with proven treatments like minoxidil and finasteride, reporting faster regrowth but mixed results regarding side effects — some find the combination beneficial, while others report increased shedding or scalp irritation.

The community also frequently compares RU58841 to FDA-approved treatments like finasteride and minoxidil. Some users switch to RU58841 after experiencing sexual side effects from finasteride, viewing RU58841 as a safer topical alternative — though this remains anecdotal without clinical backing.

In summary, community feedback paints RU58841 as a promising but risky option for hair loss. Users who tolerate it often praise the regrowth results, while others report serious side effects or inconsistent DIY outcomes. The consensus leans towards caution, emphasizing that RU58841 remains unapproved and lacks long-term human safety data.

Potential side effects: Strange surprises or exaggerated fears?

Anecdotal reports from forums and user communities frequently mention side effects like scalp irritation, shedding (which is common with many hair loss treatments due to hair cycling), and even fatigue or brain fog. However, these are self-reported and not backed by clinical data, making it difficult to determine whether they stem from RU58841 itself, improper formulation, or other factors.

More concerning is the unknown long-term impact. Since RU58841 binds to androgen receptors, there’s a theoretical risk of receptor desensitization — where the body adapts, leading to reduced effectiveness over time or even hormonal imbalances. Additionally, if enough of the compound is absorbed into the bloodstream, it could potentially interfere with androgen-dependent processes elsewhere in the body. This remains an open question due to the lack of long-term human studies.

RU58841 remains an experimental compound. Those considering it must carefully weigh the potential benefits against the significant unknowns — particularly the absence of large-scale human trials and regulatory oversight. While early studies and user reports are intriguing, the long-term effects, proper dosage, and risks of systemic absorption are still unclear.

In short, RU58841 represents a fascinating glimpse into the future of targeted hair loss treatments, but it’s not without its uncertainties. For those willing to take the risk, caution and informed decision-making are essential.

References

Battmann, T., et al. (1994). "Antiandrogenic activity of RU58841 on sebaceous glands in golden hamsters." Journal of Steroid Biochemistry and Molecular Biology, 48(4), 409-415. Retrieved from https://doi.org/10.1016/0960-0760(94)90094-9

Sato, T., et al. (1998). "Hair regrowth in macaques with topical application of the nonsteroidal antiandrogen RU58841." Journal of Dermatological Science, 16(1), 29-35. Retrieved from https://doi.org/10.1016/S0923-1811(97)00134-3

Zhou, W., et al. (2004). "Systemic absorption of topical anti-androgens in rats." Toxicology and Applied Pharmacology, 194(3), 318-325. Retrieved from https://doi.org/10.1016/j.taap.2003.10.003

U.S. Food and Drug Administration. (n.d.). "Drug development and approval process." Retrieved from https://www.fda.gov/drugs/development-approval-process-drugs

National Institutes of Health. (n.d.). "Clinical trials and drug safety." Retrieved from https://www.nih.gov/health-information/clinical-trials

Reddit. (2025, February 21). Is it better to buy RU58841 topical serum or just buy RU58841 powder and make it yourself? Retrieved from https://reddit.com/r/tressless/comments/1iugzpw/

Reddit. (2025, January 31). Is anyone using RU58841 against acne? Retrieved from https://reddit.com/r/tressless/comments/1iefsgk/

Reddit. (2025, January 14). Methods Of Staying Safe On Ru58841 - My 2 Cents. Retrieved from https://reddit.com/r/tressless/comments/1i0x5po/

Reddit. (2024, December 28). Anyone who used RU58841 without fin/dut? Retrieved from https://reddit.com/r/tressless/comments/1hntviz/

Reddit. (2024, December 23). A scary individual report of RU58841. Retrieved from https://reddit.com/r/tressless/comments/1hkieio/