T Nation

The Dangers of 5-Alpha Reductase Inhibitors


I was asked in a PM: "What is your view on DHT blockers like Propecia?"

Propecia is but one drug classified as 5-alpha reductase inhibitors.

I have something controversial to say. Bring on the debate.

These drugs are xeno-testosterones [I coined that], look at molecular structure. Transported as a steroid chemical to every cell nuclei in the body where gene expression is altered [well documented]. For a few, this created permanent epigenetic changes to DNA or to processes that transcribe the DNA, which might be secondary to other DNA expression changes. How can we trust that? One doc called out an alarm that these drugs can, even with a single dose, sexually cripple men. We have had a few young guys here who had hair loss who had their lives ruined. As they loose LH/FSH levels, it would seem that the hypothalamus is broken. But one would want to administer a trial of a SERM to better understand that. As steroid drugs can affect different genes, there may be changes beyond the obvious or expected. What other important steroid metabolism processes are shutdown? When these guys go on TRT, is there any effect that prevents TRT from working properly in terms of a response to restored T levels?

Why are some guys vulnerable to this damage? Probably from the natural variations in DNA methalization that expose some DNA for transcription and hiding many other genes in the DNA. This creates traits that go well beyond DNA code changes. These methalization changes can be trans-generational, responsible for some of the things that we inherit from our parents. It is well documented that women who were subjected to starvation during WW-II pass on effects that can be seen in their children and grandchildren. So a susceptible methalization trait can make one vulnerable to epigenetic changes that most would seem to avoid.

The 5-alpha reductase problem is probably a result of changes to DNA methalization. For some, this is DNA [expression] poisoning.

When you read about how some body builders can't recover after a cycle with what seems to be a permanent HPTA shutdown; consider that the high steroid doses can really accelerate hair loss. The use of 5-alpha reductase inhibitors in this group is wide spread. It is easy to connect the dots. Some of these HPTA disasters for body builders are from the 5-alpha reductase inhibitors, not from poor post cycle therapy [PCT].

Also consider a man who has an enlarged prostate. He is probably suffering from elevated E2 and declining T levels at his age and condition. That is a double hit on the E2:T ratio. If he is prescribed a 5-alpha reductase drug, if he is normal, the resulting drop in DHT levels can kill his already waning libido. If libido is dead, ED drugs will not work. DHT is essential for the development and maintenance of the sex organs and mission critical for libido. Some men will drop the drug in an effort to recover their libido and sense of being a male. A few of these will not recover to any degree. With a dead HPTA, their DHT levels will also remain low - what a benefit! With a known prostate condition, his doctor will probably then refuse TRT. There are effective prostate supplements that are safe and effective. It is a doctors job, it seems, to prescribe drugs, not supplements. And there is no way to get insurance or Medicaid to pay for the supplements. Only FDA approved [poisons] are allowed. Many who stop the drug, can recover and then manage their condition with a supplement type product.

For some 5-alpha reductase inhibitors are permanent chemical castration. They cannot make their wives pregnant unless they are on TRT. And if they are not using hCG [or a SERM - which has issues] fertility is then also in doubt or time limited.

We sometimes also see cases of permanent HPTA damage with deca only steroid cycles. I also regard deca as a dangerous xeno-testosterone for some. One can then regard all synthetically structured steroids as suspect. Many will use deca at it does not metabolize into DHT. Sounds hair friendly enough.

There is no way to know in advance who will be effected. The risks are not widely known, but even if they were, many young men are disposed to ignore risks.

Propecia: http://en.wikipedia.org/wiki/Finasteride

5-alpha reductase inhibitor: http://en.wikipedia.org/wiki/5-alpha-reductase_inhibitor

5-alpha reductase: http://en.wikipedia.org/wiki/5-alpha_reductase

Also effect the nervous system: "Another function of the enzyme is participation in the creation of such neurosteroids as allopregnanolone and THDOC."

Neurosteroids: http://en.wikipedia.org/wiki/Neurosteroid

Deca: http://en.wikipedia.org/wiki/Nandrolone


I have used TD pregenolone which can lower 5 alpha reductase with out nasty side effects.


Just confirming - it does that by boosting Progestrogen which interferes with 5ar T-to-DHT conversion, correct?


That is the science behind it and does make sense, but it may be something total different.


I have been taking propecia for about 6 months now, i havn't to this stage really noticed any side effects. Very recently in the last few weeks i think my libido has been a lil low...but nothing crazy different.

My question is how can you tell if you are one of these people who reacts badly to it, and how long would it take to react this way?

I have always been very worried about taking it, took a long time to talk myself into taking it...

Would like any feedback..


As far as the above comments go, on the portion pertaining to deca...... Wouldn't it be more accurate to say "long term" vs. "permanent" with deca only cycles?
I have researched greatly and found that many users of deca and deca only suffer sides that eventually do go away.....

Many times 18 months to 2 years....... I've yet to find one that regained high test levels and didn't eventually recover.... Dr. Michael Scally has seen no cases of deca users not recover eventually....... Dr. swale has heard of regained test levels and not regained sexual function one very very few cases... Not enough to count on one hand.......

Thanks man


A lot of guys who have problems from propecia have normal LH/FSH and normal or even high T levels, so I doubt that is what is going on.


Correct, there is more to it than test levels only.
When deca creates dysfunction, many users have recovered their levels and still suffer dysfunction. Generally nothing helps not caber not going back on test and not another PCT........ The finger gets pointed at an unknown reason..
The cases I've seen of dysfunction caused from deca appears to linger for 18 -24 months.... I have yet to hear of a case where a used recovered his levels and waited the 18-24 months and did not recover....... If your out there ....chime in!


Just to add to the discussion: isotretinoin (brand name Accutane), which is used to treat severe acne, also inhibits 5-alpha reductase.

There is a forum (can't remember the name) that discusses the nasty sides of accutane. There were many people with libodo/sex life problems.


I had a total shut down 29th Jan 2012, never forget it, it was instant, day before I was my usual self, morning wood and 2 rolls in the hay.
That night, had a few drinks, and did feel a bit ill, ED for the first time ever, it has never come back.
First few days i thought it was the flu/illness, but no.
It was right at the end of a test deca cycle, not a heavy one by most standards, almost TRT ranges from what I see some boys shoot, but I am very sensitive to gear.

Did Scally’s restart 3 times, even had consults with him.
Levels all came back to normal and even Scally said I should be good to go, nope, zero sex drive since then.
I even tried TRT, might get a week of ok function, maybe 10-20% of what I had before, then crash, tried many different protocols and dosing, just couldn’t get dialed in.
Even tadafil doesn’t give me wood now, headache and all of the sides, still old floppy.
So there you go, you found the busted guy lol


Please read the stickies found here: About the T Replacement Category

  • advice for new guys
  • things that damage your hormones
  • protocol for injections
  • finding a TRT doc
  • HPTA restart

The prospect of a restart after 5-apha reductase damage is bleak.
However, Scally’s restart protocols are insane as doses are too high - and more.
see the HPTA restart sticky for comparison.