Everything You Need To Know About RU-58841 For Hair Loss

People are all very different. I say this because it rings especially true in the case of hair loss, and even more so for the treatments we use for it.

Some people can regrow a full head of hair using only one treatment while others can use ten different treatments and see no progress whatsoever. If you are part of the latter group, traditional treatments like finasteride and minoxidil may not work for you, and unless you want to give up and shave it off, you may need to look at alternative options. One such option is called RU-58841 (for the sake of convenience I will be abbreviating it as RU).

This article is going to explore RU in depth taking a look at how it works, how effective it is, and finally, my opinion on if it is worth considering, all to give you a better understanding of this relatively obscure, yet noteworthy hair loss treatment.

What is RU-58841?

RU is classified as a topical nonsteroidal antiandrogen. It was originally developed in the 1980’s to address androgen related disorders such as acne, hirsutism, and, you guessed it: hair loss.

RU came to fruition because scientists wanted to create a nonsteroidal antiandrogen medication that would only have an effect where it was applied. Many drugs similar to RU are systemic, meaning that they effect the entire body, whereas RU was meant to be different because it would only affect the direct area of application.

During initial tests conducted on hamsters and rats, RU was shown to be very promising; even at very low doses. But, despite the initial findings, something happened to the company that caused them to drop the project (to this day no one is quite sure what happened).

It was only a couple years later than a company called ProStraken took it upon themselves to try to explore RU more in depth. They ended up renaming it to PSK3841, so if you read or hear information about PSK3841, remember that it is the same thing as RU-58841. It seemed that ProStraken was making profound discoveries about RU because in 2005 they announced that they would be ready to launch a product to the public by 2010. But once again, plans fell through.

That leaves us where we are today: we know some information about RU from several studies that were conducted before it was shelved, but there has been no maturation in terms of development of an easy-to-access product for public use. Unfortunately, since studies ceased, it is still deemed an “experimental drug”, meaning that the FDA has not approved it which makes it difficult to obtain as it cannot be prescribed or sold in stores.

How does RU-58841 work for hair loss?

Like previously stated, RU is an antiandrogen. But, to understand how that affects hair loss, you first need to understand what androgens are and the role they play in androgenic alopecia (pattern hair loss).

As you may have inferred: the term “androgenic alopecia” is derived from the prominent role that androgens play in hair loss. Androgens are hormones that are present in both men and women, but more concentrated in men because they are crucial to male sexual development.

A certain androgen that you may have heard of: testosterone, is what is responsible for hair loss. Well not testosterone itself, but rather a byproduct of it called dihydrotestosterone (DHT), which is also an androgen. Testosterone is converted into DHT by an enzyme called 5-alpha reductase (5-AR: it is what finasteride works to block).

Although DHT is important to the overall healthy functioning of the body, it causes hair loss in people that are genetically sensitive to it. It does this by binding to androgen receptors that are present in the hair follicles, and even though this process happens in everyone’s hair, only people that are sensitive to DHT will experience hair loss (or so scientists theorize). This is where RU may be able to make a significant impact.

Instead of blocking 5-AR like finasteride, RU works in a completely different way to block DHT: it suppresses the androgen receptors. This is significant because instead of reducing the amount of DHT in the body, RU instead blocks DHT from binding and causing damage to the hair follicles. In case you haven’t already discerned this: RU is not systemic because it acts only where it is applied instead of reducing DHT levels throughout the body. This is why in the future (with more studies conducted) RU may be able to outshine the popular DHT blockers.

Does this sound too good to be true? Maybe, but there have been a couple of important studies done on RU that have revealed some pretty profound information.

The first study (1) took 20 scalp grafts from middle aged men with androgenic alopecia and grafted them onto nude female mice. All the grafts were conditioned with adequate amounts of testosterone. The mice were split into two groups: a control group and a group treated with RU. After five RU applications a week, for six months, the groups were reassessed.

It was found that in the control group there were 28 follicles, and only two (7%) of them initiated a second hair cycle. Conversely, in the RU group there were 29 follicles, eight (28%) of which initiated a second growth cycle. This is a very significant difference of showing that RU was 4x more successful than the control group, and, if replicated in human trials, this would rock the hair loss world (let’s get going on this scientists!)

The second study (2) we need to consider took a look at finasteride vs. RU. Its efficacy was evaluated in the bald scalps of 20 macaques. For finasteride, the results were taken at 0 and 6 months and for RU at 0 and 4 months. The results were astonishing.

It was revealed that finasteride, on average, increased hair size by 82%, which sounds great. But when you compare it to the 103% increase shown by RU, it is blown out of the water. This is very significant, so much so that the scientists concluded that blocking androgen receptors may be a more viable method of combatting hair loss compared to inhibiting 5-AR.

Side effects

It is very important to note that if you take RU, it is at your own risk.

There have not been long term studies conducted on RU so the long term side effect profile is virtually unknown. Like I said at the beginning of the article, everyone is different and therefore may have a different short, or long term reaction to taking RU. Any and all side effects are purely anecdotal at this point coming only from people online. That being said, some of the commonly reported side effects are:



Blurred vision

Chest pain


Be very cautious and make sure to inform your doctor of your RU use.

In conclusion

Is RU worth trying?

In my opinion, yes, but again be careful. There is a lot of anecdotal evidence online that supports the notion that androgen receptor blocking may be equally, if not more effective than blocking 5-AR. This alongside the exciting scientific findings that we have make a good case for RU.

Personally, I would recommend approaching RU with a skeptical outlook. Certainly don’t depend on it entirely, and use it without any expectations. That way, if it doesn’t work you wont be disappointed. The only problem is finding a legitimate play to get some (I’m still trying to find one).

Just like a house needs a strong foundation, so does your hair.