Finasteride Side Effects FAQ



[Size=4][b]NOTICE (Feb 2011):

If you are suffering from PERSISTENT Finasteride side effects, please participate in Dr. Irwig’s NEW 2011 study on Testosterone, DHT & Fertility parameters.

VIEW STUDY DETAILS: viewtopic.php?f=33&t=4815

[Size=4]We invite you to be a part of this important project so that he can report the hormone levels and fertility parameters in men who developed persistent sexual side effects after taking finasteride for male pattern hair loss. [/size]

Dr. Irwig’s previously published study can be seen here: viewtopic.php?f=33&t=3497

Finasteride Side Effects Group FAQ

NOTE: If you are experiencing an adverse reaction to Finasteride, either while ON the drug or AFTER quitting, PLEASE REPORT IT TO THE APPROPRIATE AGENCIES:

Merck National Service Center: 800-444-2080

Canada (Health Canada):



For other countries, please contact your appropriate agency.

[Size=4]VIDEOS about the Post-Finasteride Syndrome:[/size]

Dr John Crisler - The Post-Propecia Syndrome: Permanent Side Effects

Swedish TV News investigation into Permanent Finasteride Side Effects:
Translation: viewtopic.php?p=2777#2777

Swedish TV UPDATE: Permanent Erectile Dysfunction NOW OFFICIAL IN EUROPE:

Update to original news story, Merck’s response:

Swedish Medical Agency concludes permanent Erectile Dysfunction investigation, now listed as an official side effect in Europe:

1) What is Finasteride and what does it do?

Finasteride is an anti-androgenic drug (a 4-azasteroid – a testosterone analogue, codename “MK-906”) which selectively inhibits Type II 5 alpha-reductase, the enzyme responsible for converting testosterone to dihydrotestosterone (DHT) in mice, rats, monkeys, and humans.

The Type II 5 alpha-reductase isozyme is primarily found in the prostate. Type II 5 alpha-reductase is also present in genital skin, seminal vesicles, epididymides, hair follicles and the liver, and is responsible for two-thirds of circulating DHT.

By blocking the conversion of Testosterone to DHT, Finasteride produces significant decreases in circulating serum and tissue DHT concentrations via a shrinking of the prostate. In fact, oral dosing with a 1 mg tablet will reduce serum DHT concentration within 24 hours by ~70%. Finasteride has also been found to cross the blood-brain barrier.

Besides this, Finasteride also:

  • blocks Progesterone --> Allopregnanolone conversion, thus interfering with GABA-A receptor function in the brain (anxiety, possible seizures, depression)
  • blocks 5ARII reduction of dihydroprogesterone and allotetrahydrodeoxycorticosterone (THDOC)
  • blocks the 5alpha-reduction of androstenedione to androstanedione
  • Reduces NOS (nitric oxide synthase) via inhibition of DHT (DHT mediates NO, NO is required for erections, amongst other functions)
  • Shrinks the prostate and causes involution (progressive loss of function) via prostate cell apoptosis (death)
  • Elevates Testosterone levels by up to 15%-20% while on the drug, which can cause aromatization of extra/increased Testosterone into Estradiol, thus disturbing the androgen/estrogen ratio.
  • Can lead to increased Estradiol via reduction of DHT (DHT is an antagonist of estrogen and keeps it in check)
  • Can lead to an accumulation of Progesterone
  • Can lead to depression and gynecomastia (male breast development) due to elevated Estrogen levels
  • Can lead to increased liver enzymes (Finasteride is metabolized in the liver by the P450 cytochrome system)
  • and other issues which have yet to be identified

Finasteride is the active ingredient in Propecia and Proscar, drug brands marketed to men for hairloss and BPH (benign prostate hyperplasia) treatment by Merck & Co., Finasteride’s manufacturer.

Unfortunately, although DHT is intimately involved in both the hairloss process and BPH, it is not the “evil” male hormone the pharmaceutical industry has labelled or marketed it to be.

On the contrary, medical research shows DHT and 5AR Type-II are absolutely critical for male libido (sex drive), maintenance of proper genital tissue structures/size/function, seminal fluid production, keeping Estrogen/Estradiol levels in check, mental clarity/function (via assisting the conversion of various neurotransmitters/neurosteroids in the brain), and numerous other important and as-of-yet unknown functions in the male body.

For further proof of these claims, we invite you to review the medical literature and studies posted in the “Medical Research” section of this forum: index.php?c=5

2) What is this group and why does it exist?

This group is comprised of men of different ages who took the drug Finasteride (aka Propecia, Proscar, or other generics such as Finpecia) for varying periods of time, at various dosages, for either cosmetic (hairloss) or medical (BPH) reasons.

All men on this forum suffer from side effects that occurred during their usage of Finasteride, or which manifested themselves after they quit the drug.

For many men, the ultimate factor in their decision to take Propecia or Proscar was the assurance by Merck & Co.‘s medical literature and their doctors’/dermatologists’ statements that any side effects experienced would be reversible upon cessation of the drug.

Unfortunately, resolution of these side effects has yet to occur. This is contrary to Merck’s (the drug’s manufacturer) claim that any and all side effects are reversable upon discontinuation of the drug.

Although while taking Finasteride a man’s Testosterone production may be elevated by as much as 15%, after quitting the drug, some have seen their body’s endogenous production of Testosterone, DHT, Luteinizing Hormone (LH) and Follicular Stimulating Hormone (FSH) plummet. This has left certain men in a state of Secondary Hypogonadism, sometimes with seriously elevated Estrogen/Estradiol levels or numerous other hormonal imbalances and health issues which are quite difficult to treat.

For futher proof of these claims, we invite you to review the member stories and hormone charts in the “Personal Profiles” section of this forum: index.php?c=3

3) Wasn’t there a Yahoo Finasteride Side Effects group similar to this?

Yes. In fact, the group was originally formed in 2003 on Yahoo, at the following address:

As membership for the Yahoo group grew to 1000+ people over 3 years, it was decided that a newer, easier-to-use forum was needed to help categorize and track the wealth of information collected – hence, this forum was born.

Note that the Yahoo group will still be available as a repository of past information, and can be referenced at any time by members who have access to it.

4) What side effects are typically reported by members of this forum?

* Loss of Libido / Sex Drive / No more response to sexual, visual or erotic stimuli
* Severe Erectile Dysfunction / Complete Impotence
* Complete Loss of Morning / Spontaneous / Nocturnal Erections
* Genital Tissue Changes (penile narrowing, shrinkage, curving, numbness, wrinkling; scrotal shrinkage, numbness, loss of pubic hair)
* Lack of blood flow to penis / Cold penis & scrotum
* Loss of genital sensitivity / Loss of pleasureable tactile response (feels numb, like touching arm or foot)
* Emotional Blunting / Emotionally Flat / Loss of pleasureable feelings & emotions
* Cognitive Dysfunction / Inability to process or comprehend information clearly, easily or quickly
* Memory Impairment / Forgetfullness (can't recall names, places etc) / Constant blanking out & losing Train of Thought
* Loss of Motivation / Aggressive Drive / Listlessness
* Watery Ejaculate
* Reduced Ejaculate
* Ejaculatory / Orgasm Anhedonia (loss of pleasureable feeling from orgasm)
* Testicular Pain
* Testicular Shrinkage / Loss of Fullness
* Extreme Anxiety / Panic Attacks
* Depression
* Persistent chronic fatigue / loss of strength & stamina
* Gynecomastia (male breast development)
* Sleep disturbances (loss of REM sleep / dreams, constant waking during night, loss of refreshing deep sleep, loss of erotic dreams)

Some of the less common side effects experienced are:

* Muscle wasting & atrophy (particularly in forearms/wrists/hands, and lower legs/shins/thighs)
* Constant body-wide muscle twitches (fasciculations) & muscle quivering (often affecting fingers, arms, legs/thighs, stomach, shoulders and/or face) 
* Body feminization changes -- female body fat/pubic hair/muscle redistribution patterns, hip & breast (gynecomastia) size increase
* Lowered body temperature / decreased metabolism / decreased androgenicity
* Loss of tongue motor control -- slurring of speech, constant stumbling/tripping over words
* Penile tissue fibrosis / scarring / Peyronie's Disease 
* Stomach Pains / Digestion Problems
* Blurry vision / acuity decrease 
* Prostate damage / pain / infection
* Emergence of white (pigmentless) pubic / scrotal or facial / scalp hairs
* Dry/Dark circles under eyes (unknown how Finasteride causes this but reported by many users) 
* Liver damage (elevated AST/ALT levels) 

5) I’m currently taking the drug, experiencing side effects and want to quit. How should I quit?

Firstly, unlike other medications whereby reducing dosage would reduce the medications effect, Finasteride does not operate in this manner due to its extreme potency against the 5AR2 enzyme and resultant DHT surpression, whereby it can take up to a week or more for DHT to even begin to return to baseline after a single dose, as noted here: viewtopic.php?p=12187#12187

In addition, Finasteride has a near-flat dose response such that 0.05mg inhibits nearly as much DHT as 1mg, as evidenced here: ).

Thus, the question is: should I quit cold turkey or ween off the drug? Obviously the sooner one can get off the drug, the better. We have no evidence that either method will make a difference in terms of “avoiding” side effects after quitting, but going by common sense, we believe it makes sense to ween off in order to help reduce shock to the endocrine system. Additionally, according to Dr. Crisler, DO ( ), weening off over several weeks is advisable.

If you are taking Propecia, we recommend gradually reducing the dosage from 1mg to 0.5mg (half a pill) to 0.25mg (quartered pill) to 0.125mg (8th of a pill), to 0.0625 (16th of a pill) over time while increasing the days between dosing (ie instead of taking it everyday, take it every every 3rd day, 5th, 7th and so on), until you are ultimately no longer taking the drug.

If you are taking Proscar, same concept – reduce from 1.25mg/day (quartered), down to 0.625mg (8th) and possibly 0.313mg (16th of a pill – if even possible to split it this much), over time.

Before you quit, it is also recommended you take bloodtests as outlined in section 6. This is so that you will have evidence of Finasteride’s effects on your hormones while on the drug, to compare against after quitting.

6) I quit Finasteride and am still experiencing side effects several days or weeks after. What’s going on?

If you just quit Finasteride, give it a few weeks to allow your body to recover on its own before you assess your next steps. The vast majority of men recover without issue after quitting the drug, so there’s no need to panic at this stage!

Since it can take a minimum of one week for DHT levels to return nearly to baseline after a single dose of Finasteride, and due to the very slow off rate of the 5AR-II enzyme (~ 30 days), watch for the feeling of DHT returning to your body approximately 1-2weeks/a month after your last pill, and correspondingly the waning of side effects experienced while on the drug.

On the other hand – if you do recover to your pre-Finasteride state, only to find it short-lived (a few weeks/months at most, followed by the return of side effects in full force), then you should consider further bloodtests to see what is happening with your body via a full hormone profile:

Type of blood tests to get (NOTE: GET TESTED BETWEEN 7AM-9AM, when Testosterone levels are HIGHEST in the morning):

Total Testosterone
Free Testosterone
Bioavailable Testosterone
DHT (not accurate compared to Adiol-G)
3alpha-diol G (Androstanediol glucuronide-- “Adiol-G” for short): metabolite of DHT, measures 5AR-II activity
Androsterone glucuronide (another metabolite of DHT that measures 5AR activity)
Estradiol (E2)
Estrone (E1)
Total Estrogens
17-OH Progesterone
17-OH Pregnenolone
Free T3
Free T4
CBC or FBC (Complete Blood Count/Full Blood Count)
LFT (Liver Function Tests - AST, ALT, GGT, Bilirubin, etc.)
Androgen/Estrogen ratio
Testosterone/DHT ratio
17-ketosteroids (24-hr urine sample) –

[Size=4]The following labs in the USA CAN TEST FOR 3a-diol G, here are the test #s:[/size]



More on 5AR2 activity testing – READ HERE:

In addition, you may also want to consider obtaining the following tests to test for possible erection, blood flow and veinous leakage issues:

These erection function tests may provide additional insight into your condition and further aid in treatment.

7) It’s been months, I have yet to recover and have obtained the above recommended blood tests. Now what?

The objective from this point forward would be to find doctors, endocrinologists and urologists knowledgeable enough to recognize Finasteride’s dangerous effects on the endocrine system, having them believe your case and then be willing to work with you to identify possible hormonal/other issues and treatment options if you have yet to recover on your own.

At this stage, be prepared to face much adversity from the very medical community which prescribed you the drug in the first place. Most likely you will be told that all symptoms are “in your head” and that Finasteride could never cause such problems. They will likely quote that Merck’s medical literature states that all side effects resolve after discontinuation of the drug. They may also prescribe other drugs such as Viagra or Cialis to help with erectile dysfunction – while potentially helpful in the short-term, be aware that these are simply bandaid solutions and do not address the root causes of our Post-Finasteride syndrome.

Thus, before undertaking such appointments it is advisable that you read and educate yourself via the Studies section of this website. Consider printing out and highlighting the relevant materials, and consider bringing them with you to your appointments to discuss. Hopefully the medical professional will take an interest in the material and rethink your case; if not, you’ll need to move on again until you find one who does.

Ultimately, besides the side effects themselves, this is possibly the most frustrating and tiring process of dealing with the post-Finasteride syndrome – the ignorance of the (majority) of the medical community in recognizing the possibility that such persistent side effects exist, and dealing with medical professionals that claim nothing can be done to treat them (false).

8) Does anyone recover from Finasteride side effects?

For the majority of men, they recover without issue; unfortunately for a small percentage (members of this forum and others out there), these side effects persist… and unfortunately the medical community does not have definite answers as to why (yet). Thus, while most Finasteride users generally recover from side effects in a short time frame (often in weeks/months), for some it may take much longer, sometimes years… or in some cases, they only recover up to a certain point. As each person’s endocrine system and situation is different, there are no guarantees.

For those with more “permanent” problems, natural supplements, excercise and consistent weight training can help somewhat. However, for those that have ended up with near hypogondal levels of Testosterone/elevated Estrogens as a result of the drug, some have required the assistance of additional drug treatments to try and stimulate their Hypothalamic Pituitary-Testicular-Axis (HPTA) to produce more endogenous Testosterone/DHT, and/or reduce elevated Estrogen levels (for starters).

Common endogeneous Testosterone-boosting drug treatments include:

  • Clomid (Clomiphene Citrate)
  • hCG (human Chorionic Gonadotropin)
  • Nolvadex (Tamoxifen)

Common estrogen reducing drug treatments include:

  • Arimidex
  • Nolvadex (Tamoxifen)

Still others have attempted to recover by going on Hormone Replacement Therapy – mainly Testosterone Replacement Therapy (TRT), which involves injecting or applying a patch containing extraneous Testosterone to boost one’s levels accordingly.

Unfortunately, TRT is often a lifelong commitment with its own set of issues, as the body senses the extraneous Testosterone and thus shuts down it’s own endogeneous production… the result of which can lead to testicular atrophy and sterility (unless hCG is used in conjunction with TRT to maintain fertility). Nonetheless, TRT is probably the “ultimate” attempt to correct Post-Finasteride induced low Testosterone – but should only be undertaken as a last resort, as even then there are no guarantees it will correct Finasteride-related issues 100%.

Be aware that there may also be many other hormone imbalances which can be commonly overlooked as a result of Finasteride use (ie, some men present with elevated Prolactin, elevated Sex Hormone Binding Globulin – aka SHBG, etc.). Thus, it is imperative to obtain a full hormone profile to assess your situation, and work with a knowledgeable medical professional who will help select the proper drug treatment course, depending on your bloodwork results.

It also goes without saying that each of the above treatments should be evaluated in terms of their own associated risks and/or side effects. As such, the decision to pursue any further medical treatment should not be taken lightly, and only under the care of a competent medical professional (if you can find one willing to take your case).

Finally, be aware that while some have completely recovered via medical intervention, there have been others who have tried all of the above and have yet to recover 100% to their pre-Finasteride self (but may nonetheless approach it). Again, as each person’s situation and endocrine system is different, your personal recovery capability and response to any potential treatments will vary.

Some recovery stories can be seen here: viewforum.php?f=22

9) I had my hormones checked and was told all my results are in range.

This is a common misconception you will likely come across in dealing with unknowledgeable medical professionals. Hormone levels operate on different levels for each individual, and its hard to know what levels you operated on prior to using Finasteride, unless you took a baseline hormone profile before commencing use of the drug.

As a general rule a young person should have Testosterone, Free Testosterone, and DHT in the upper third of the reference ranges, with Estradiol and Estrogen in the mid ranges for optimal performance. Deciding if a person is OK or not based on a large range is an outdated protocol which the medical field has yet to address. Such ranges are taken as an average from people aged between 18 - 80 years old.

Unfortunately most doctors do not think of, or entertain the need to require blood tests prior to starting Finasteride. Having a pre-Finasteride baseline hormone profile would be your evidence that Finasteride disrupted your hormone balance post-use. Unfortunately, very few men obtain such pre-drug baselines, and are thus at a disadvantage because they have nothing to compare their post-Finasteride bloodtests against.

An example of optimal ranges can be found here:

10) Do you have any recommended doctors that have experience dealing with Finasteride-induced side effects?

Dr. John Crisler –
Dr. Eugene Shippen – Author of The Testosterone Syndrome
Dr. Irwin Goldstein –

These are a few of the top doctors who recognize finasteride is a problem and have treated many patients suffering from its side effects.

Group Etiquette:

  1. No slandering of group members

  2. Do not post anything which will be offensive to other members

  3. Disagreements are allowed, but please present your facts. and refrain from insulting one another.

  4. If you have studies you can reference please include them in your post

  5. When topics are changed during a thread, please also change the subject of the thread.

Please keep this group as professional as possible

[i]Disclaimer: The information and opinions expressed on do not constitute professional medical advice.

Readers acknowledge and absolve the forum owner of any legal, financial or personal responsibilities, repercussions, liabilities, damages or harm that may arise as a result of the use of the information contained on[/i]

1 Like