If you are one of few unlucky people who can’t tolerate 5ar inhibitors and are extremely sensitive to drop in DHT, this post might be for you. I got sexual side effects with even saw palmetto and any 5ar inhibitor gave me extremely high side effects. I did some research and there may be people who might find some of what I found useful.
My approach here would be to optimize for side effect profile than efficacy. Maintenance or slowing down loss is what my goal is.
Firstly, let’s examine possible reasons for side effects with finasteride:
- Finasteride inhibits isoforms of DHT unevenly. It is possible that your body does not like this inbalance.
- T/E ratio getting distorted from excess aromatisation.
- DHT is a potent androgen and inhibiting it is akin to androgen deprivation. Some people with high other androgens and high AR sensitivity in gene(can be checked with CAG repeat test) won’t have issues or will have AR upregulation to account for this. But others who are hypogonadal or have non-ideal genes may not be as lucky.
Dutasteride is simply better
Looking at side effect rate for Propecia and Avodart from FDA label, you can see this.
You can see that the side effect rate for Dutasteride is simply better. I suspect, this could be because it inhibits isoforms of DHT more evenly. Even if you do get side effects, at around 1.5 year range, you have 3 in 1000 chance over placebo of getting side effects. Remember this is in men with prostate issues and older men who would likely have low levels of androgens to begin with and would be more prone to side effects, especially at a dose that can nuke upto 95% of serum DHT.
Anecdotally I found this to be true. After getting extremely high side effects when I first started the drug orally at 0.5mg/day, I found that around 1.5 months in, most of the side effects(including sexual side effects) were greatly reduced or were fading away. This was unlike when I tried low dose topical finasteride, where side effects persisted while continuing the drug.
Topical Dutasteride - Low Side Effects
The reason for low side effect profile with topical Dutasteride are a combination of following factors:
- 500 Dalton rule - Dutasteride has 528 dalton molecular weight, meaning it does have absorption, but not enough to completely penetrate. This is unlike finasteride, which absorbs completely with topical usage over time.
- Pharmacokynetics of Dutasteride - Dutasteride has dose dependent half life. At 0.01mg half life is 30 mins, but at 1mg this could be as high as 30 days.
- Lack of first pass metabolism in liver could mean lower side effects.
Galcare Pharma did a study which showed dutasteride absorption in scalp to be around 26%, while in the serum it’s around 6%.
So if you apply 0.025% 1ml dutasteride to scalp, you can expect to have absorption of 0.015mg into the body and 0.065mg into the scalp. Meaning you should have close to zero serum DHT inhibition with 0.025% topical dutasteride applied everyday.
Efficacy of Topical Dutasteride
I could not find any direct studies on topical dutasteride, but I could find a few on dutasteride mesotherapy. This study shows that mesotherapy of 0.01% dutasteride every 3 months paradoxically did have hair regrowth. This paper shows various studies which demonstrate good efficacy with low dose topical dutasteride(0.01%)+microneedling.
The proposed dose of 0.025% topical everyday should result in far higher scalp dutasteride concentration than mesotherapy with 0.01% weekly or monthly. I found this anecdotal result on Reddit where the user claims good result with 0.1% 1-2x/week, which is similar dosage to 0.025% everyday proposed above.
The user also claimed 20% DHT reduction when he tried EOD usage, which is consistent with systemic absorption data claimed above. Patrick Mwamba’s FUEClinic also recommends 1ml 0.05% 3x/week topical dutasteride, meaning they likely have seen good results on patients for maintenance therapy with it.
Why are there people claiming side effects with Topical Dutasteride?
If you go through Reddit posts or on forums, you will find people claim side effects with topical Dutasteride. This is simply because topical Dutasteride by many companies is megadosed. They seem to optimize for people who are scared of side effects, than people who truly have side effects.
Let’s take the case of Xyon, which I have tried and got side effects from. They advertise it as low side effect solution, but I could find user report of 42% DHT inhibition. Because of their superior vehicle, they are able to achieve 0.25% systemic absorption vs 5%, but because it is megadosed at 20mg/1ml application, you still are likely to get side effects.
It’s a similar story with other telemed clinics like Strut, Happy Head etc. Optimizing for efficacy is more profitable than catering to the very small minority that truly may have side effects.
Conclusion
For someone looking for low side effect profile solution to use as part of their stack(which would be better than using no 5ari), 0.025% 1ml/day topical dutasteride seemt so be it. I hope this research helps someone else. Please do share results of topical dutasteride usage if you have any.