How Does Dutasteride Impact Testosterone and Estrogen Levels?

In 2015, I wrote a popular post on how finasteride impacts testosterone and estrogen levels. This time, I want to examine how  the stronger DHT inhibitor dutasteride effects testosterone and estrogen levels.

Propecia (brand name finasteride) increased mean circulating levels of both testosterone and estradiol (estrogen) by approximately 15% per one study by its manufacturer Merck. See page 8 in here for more details. However, this increase is not substantial enough to cause testosterone and estrogen levels to exceed the reference range. In the same study, finasteride (1 mg) rapidly reduced serum DHT by 65% within 24 hours of ingestion.

Dutasteride, Testosterone and Estrogen

Dihydrotestosterone (DHT) blockers reduce the conversion of testosterone to dihydrotestosterone. This results in higher levels of circulating free testosterone (aka the male sex hormone).

When first researching this subject a few years ago, I expected that dutasteride would cause significantly greater increases in testosterone and estrogen levels in comparison to the weaker finasteride. See my post on dutasteride being more effective than finasteride when it comes to hair growth. Note that the former also causes higher rates of side effects in comparison to the latter.

Dutasteride inhibits DHT levels to a far greater extent than finasteride. Moreover, it inhibits both type 1 and type 2, 5α-reductase isoenzymes which are responsible for the conversion of testosterone to DHT.

I take dutasteride (0.5 mg once every 3 days), and feel like it might have given me some weight gain and gynecomastia. However, the one time I measured my estrogen (female sex hormone) level, it was within the normal range for a male. I also have a far more sedentary life than when I used to be extremely skinny (although my caloric intake has not changed). On a side note, estrogen can lead to increased hair growth.

According to the package insert from GSK (the manufacturer of Avodart brand dutasteride):

“In BPH patients treated with 0.5 mg of dutasteride daily the median decrease in DHT was 94% at 1 year and 93% at 2 years. The median increase in serum testosterone was 19% at both 1 and 2 years. This is an expected consequence of 5α-reductase inhibition and did not result in any known adverse events.”

According to the Avodart monograph from GSK, a 52 week treatment with dutasteride 0.5 mg/day resulted in:

No clinically significant change compared with placebo in sex hormone binding globulin, estradiol, luteinizing hormone, follicle-stimulating hormone, thyroxine (free T4), and dehydroepiandrosterone. Statistically significant mean increases compared with placebo were observed for total testosterone at 8 weeks and thyroid-stimulating hormone (TSH) at 52 weeks. The median percentage changes from baseline within the dutasteride group were 17.9% for testosterone at 8 weeks and 12.4% for TSH at 52 weeks.”

Dutasteride Testosterone
Dutasteride and testosterone increase. Source: American Journal of Men’s Health, Volume: 11, Issue: 1. Favaro et al.

The good news is that after stopping dutasteride for 24 weeks, the mean levels of testosterone and TSH returned to baseline. However, note that this study consisted of a very small sample size of just 26 volunteers. The FDA drug facts page on Avodart has the same information.

When it comes to testosterone, other studies also seem to indicate similar changes. For example, a 2010 South Korean study of 120 patients with benign prostatic hyperplasia (BPH) found that dutasteride increased serum testosterone levels around 15-16 percent after one year of treatment. A 2018 Japanese study concluded a 20 percent increase in both total and free testosterone levels.

Conflicting Reports on Estrogen Changes

Dutasteride Estrogen
Dutasteride caused a slight increase in serum estradiol (estrogen) levels. Source: American Journal of Men’s Health, Volume: 11, Issue: 1. Favaro et al.

I find it hard to believe that finasteride can raise mean estrogen (or estradiol) levels by 15 percent, but the stronger dutasteride has a negligible impact. I will update this post as I find more studies discussing the impact of the latter on estrogen levels in men. One study from Brazil (image on right) concluded that:

“There were no statistically significant alterations in the serum estradiol levels in the dutasteride group compared with the placebo group. But there was a slight increase in the serum estradiol levels in the dutasteride patients.”

A more recent 2020 study from Japan concluded that dutasteride increased estrogen levels by 9.4%. However, the results of this study were strange due to the fact that DHT levels only declined by around 40 percent rather than the expected 90 percent.

22 thoughts on “How Does Dutasteride Impact Testosterone and Estrogen Levels?”

  1. The clinical study that demonstrated the efficacy of the JAK inhibitor Baricitinib in alopecia areata. The results have just been published in the New England Medical Journal, and FDA approval of the drug is expected in the coming months. JAK inhibitors represent a therapy finally aimed at interrupting the abnormal immune response that is the cause of alopecia areata. In fact, they block the action of some cytokines (interferon gamma and interleukin 15) which induce and maintain the autoimmune aggression of the follicle which causes the fall and prevents hair regrowth in alopecia areata.

  2. I have experience of taking propecia during about one year. I had no any significant improvement on my head. Instead of that I had waked up follicles on my beard , especially around my lips. I have no hair free space between my lips and mustache hair. That’s sucks.

  3. I’ve been on dutasteride for about 7 years and experienced something similar. However, my testosterone levels have declined while on it while my estrogen started to become the dominant hormone. I’ve had like five rounds of blood work this past year showing it because of how tired I became, can’t lose weight, gyno pains have become annoying to deal with etc..

    My estrogen last year was 21 and has reached a high of 40 while my testosterone has declined from 727ng to around 422. It’s like impossible for me to lose fat as well and I work out 5 days a week.

    Oddly enough, I lost hair still for about five years on dutasteride and it wasn’t until my estrogen and T got off balance that my hairloss started to ease up. Less itching, growing faster etc..

    The driving factor to my hairloss is excesseive keratin and sebum that plug my follicles. When that stopped, my hair became healthy and thicker. It’s slowly coming back as I’m not doing a keto diet to lose the fat I’ve gained. I also have SIBO so I need to cut carbs out for a bit to get that in check. But yeah, dutasteride is not what I thought it to be, just like every other hairloss drug. I stuck it out for a long time, but it really messed my hormone profile up and I have been told I should be on TRT due to my free testosterone being 6 when the range here is 14-28.

    The things we do for hair =/

    1. Thanks for the great feedback and sorry to hear about the low testosterone. Seems like all the studies I read suggest a 10-20 percent higher T when on Dutasteride, so you really got unlucky :-(

      Also, per one article I read:

      “Normal total estradiol levels in men are somewhere between 20–55 pg/mL (2.0–5.5 ng/dL) and 10-40 pg/mL (1.0-4.0 ng/dL), depending on whom you ask.” For women, they can go up to 400 pg/mL.

      What kind of weight and body fat percent gain are we talking about? In my case, I would say Dut could have made me gain 10 lbs, but really no way for me to be certain.

    2. Well, your estrogens levels is still within the normal range for a man, and within a low range for a premenauposal woman…

      I am a woman, because I am 40 now i have to switched form a combines bcp to a progestative only pill that is supposed to be antiandrogenic. However with this new pill my estradiol level are going to decrease to 50 only (so no pick at 100/200 or more). Even if i am confident that with this pill and Spiro my androgen levels will still be in check, i am afraid of what will the lower estradiol will do to lt hair…

      I try to tell myself that for some men with Aga those level of estradiol are sufficient…but what if it isn’t for me …. i am so sick of this.
      My current regime is working, bummed i have to switched because I reached 40 years old.

  4. I would like to give Dr tsuji a piece of my mind for getting everybody’s hopes up for nothing. That quack of a Dr. And stemsons therapeutics isn’t going to come out to the market until at least 2035 if it’s even possible. My gut feeling is telling me its not going to be possible the human body is not going to be able to accept the cloned hair.

  5. Well I have been using avodart for a long time and it halted hair loss with minor improvements. I think a hair transplant and avodart will do the trick for most of the people.
    Anyway I started having urinary retention problems around the time I started avodart. I dont know if its related to it since I have never seen any previous reports about people having that side effect

    1. What kind urinary problems did you have and how serious? I had some similar symptoms but I just chalked it up to aging.

      1. Well I can’t empty my bladder. Some doctors call it lazy bladder symptom. There are symptoms like frequent urination, the urge to urinate again after urinating once, prolonged time to start urinating etc.
        Its really bothersome and like balding there is no cure for it but I am currently taking ubretid to ease the symptoms cause it can be severe sometimes.

  6. My testosterone levels were on 3.6 while on fin. They raised to 5.6 when I switched to dut, this was despite having taken testosterone-lowering drugs. Hopefully the raised testosterone won’t have a negative impact on the hair loss. Idk I have heard horror stories on people having their hairlines destroyed while on dut and the theory is because of higher test levels.

  7. Why people always forget about our natural 5-alpha reductase and aromatese inhibitor ? PROGESTERONE ?! Why do you think it happen with it with there is not DHT ?! Body stop to produce it, so, beside the damage that cause not longer producing enought Progesterone, it is not inhibiting the aromatase. Plus we don’t block DHT, we are blocking 5-alpha reductase ( that is part of other 8 reactions in the body, besides T to DHT ).

  8. I have a bit of a recent data point. In January 2022 I stopped taking Avodart cold turkey upon advice from my urologist due to erectile difficulties to see if it had an effect.

    At the time my testosterone levels were extremely high (1085 ng/dL; estrogen levels within range) but the urologist wasn’t too concerned.

    I had been taking Avodart for 20 years or however long it has been out. So this is the first time I have been off of it.

    My testosterone has dropped back into the high side of the reference range.

    However, since I stopped taking it I have lost 25 lbs and have much less energy, with zero sex drive. It’s almost as if my body got used to having that much free testosterone and I am having trouble adjusting to lower levels, even though they are still highish. Definitely have much less muscle mass – almost as if Avodart acted as a steroid.

    Hard to say if it’s Avodart or just aging (I’m 46), obviously.

    1. Thanks! Did Avodart regrow or maintain your hair for 20 years? Any changes to body hair? Did you take 0.5 mg/day brand name for 20 years?

      Dropping 25 lbs seems too much to just be due to quitting Avodart…unless you weighed 300 plus pounds before?

      1. Hard to say if it has helped or not because I have had 3 transplants in the last 10 years, but I suspect it certainly has helped a bit but nothing remarkable. Nothing that stopped me from holding off on the transplants at least.

        However, I really never had any side effects outside of erectile dysfunction which was so unpredictable over that period of time that I never connected it to Avodart.

        I took brand name for most of the time, 0.5 mg/day throughout the 20 years.

        My body hair definitely increased significantly after stopping Avodart over the last few months, no doubt there is a connection there.

        I actually weighed 170 lbs before so yeah it’s quite a bit of weight.

        Part of me wants to get back on it to see if either the weight/sex drive/energy returns. At least that would eliminate it as the cause.

        That said, I ordered last week some topical Dutasteride from one of those startups to see if there is a similar response or lack thereof.

  9. I have a question, do estrogen levels keep on rising or do they get to a stable level during fin treatment? Prior to fin my estrogen levels where 5 pg/ml, and 5 days later I got breast pain and puffy/dry nipples, so I went and got my blood done and my results came out 21.8 pg/ml only after 5 days on 1 mg of fin. Should I keep taking it or lower the dose?

  10. Hey guys, been on dut .5 MG eod for about 7 years. I have had 3 transplants. 2 were repairs from the first botched job. I would say I was a nw3 with thinning crown, receding hairline etc.
    I plan on doing another transplant at the end of this year to touch up my hairline that I got plugged out from the first surgery. As far as dut goes…it has definitely slowed my hairloss dramatically, regrowth in the crown as well. I know I’m doomed in the long run if it doesn’t hold my native hair, hair loss is pain for me, developing insecurities from hiding bad hair transplants, I hope one day soon something new and better comes to the market but I’ve been waiting for 15 years now..same old bs story another 5 years away. Going to hasson and Wong for my next procedure, hope I get good growth and dutasteride holds or else I’ll never want to leave the house without a hat for the rest of my life. The scars won’t allow me to shave my head either. Wish me luck guys. I’ve been reading this blog since the beginning. Love you all.

  11. I know I didn’t touch down on the test and estrogen topic. I feel good, libido is strong and I weight train at least 3 times a week. About 7 months ago I started to micro needle and also started taking oral minoxidil .5mg daily. I don’t want to think about the repercussions right now, that would get me too depressed to continue with life with some normalcy. I haven’t been happy with my hair since I was young and dumb and got a cheap hair transplant and ever since that day 15 years ago I’ve never felt like myself or as confident. I’m still chasing hairloss and a normalish hairline and pray this next transplant will give me that for at least a little while. Sorry I’m venting guys and girls. It’s been tough living with that fateful decision when I was 21. Ps. Dut has helped me retain most of my nw3 native hair and crown. I’ve only had my frontal 3rd transplanted x3. With subpar results.. I do get sheds on and off as well..Will keep you guys updated if any health changes happen being on these medications.

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