Finasteride (prescribed as Propecia for baldness and Proscar for enlarged prostate) appears to have serious and potentially long-lasting sexual side effects such as lowered libido, impaired ejaculation and disappointing orgasms. More about this in a moment.

When we first learned about finasteride we were excited. It was medical anthropology and drug discovery and it made for a great story. Over 30 years ago reports started surfacing about a strange sexual transformation that occurred in some remote villages in the Dominican Republic. A 1974 study published in Science on these “pseudo-hermaphrodites” explained what was going on.

Among 13 families in the village of Salinas, babies were born with what appeared to be female genitals. These children were raised as girls until puberty, when a deepening voice, the descent of the testes, and the development of a penis from what had previously appeared to be a clitoris signaled that these individuals had become young men.

The scientists discovered the explanation for this phenomenon, which the villagers termed “gueve-doces,” roughly translating as “penis at twelve.” These individuals had a hereditary lack of an enzyme needed to convert testosterone to dihydrotestosterone (DHT).

This unique medical phenomenon could have disappeared without a trace had it not been for researchers at the Merck pharmaceutical company. They noted that the lack of this enzyme produced some positive benefits: These men did not develop prostate problems or become bald as they aged. Lack of DHT was thought responsible for these benefits. The Merck researchers were able to duplicate this genetic quirk in the laboratory through a compound called finasteride, which blocks the conversion of testosterone to DHT.

This drug was first marketed as Proscar in 1992 to help shrink enlarged prostate glands. That same year Merck scientists began a research program to determine whether the drug (under the name Propecia) would also help against male pattern baldness. Instead of testing the 5 mg dose of finasteride used in Proscar, the investigators employed one-fifth that amount (1 mg). After one year, patients had on average 86 more hairs within a one-inch test circle, while those on placebo actually lost on average 21 hairs. A self-assessment questionnaire showed that 58% of those on the drug were pleased with the results, compared to 35% of those on placebo. The investigators reported a 65% increase in hair with the drug vs. 37% without. A panel of dermatologists who reviewed “before” and “after” photos judged that 48% of those on Propecia had visibly increased hair growth, as contrasted with 7% of those taking the placebo. More importantly, the men could actually see the improvement, and so did their friends and relatives.

Propecia never turned out to be the giant blockbuster that some people anticipated. It works, but the drug is not exactly a “cure” for baldness. Men have to keep taking the pill on a daily basis and there is a growing recognition that finasteride has some disconcerting side effects.

During clinical trials, finasteride was found to decrease libido, decrease the volume of ejaculate and cause impotence in some of the men being treated for enlarged prostates. This was at a 5 mg dose in Proscar. We suspect that most doctors assumed that the much lower dose (1 mg) found in Propecia would be less likely to cause such sexual side effects.

Five years ago we received the following question:

Q. “I read that Proscar and Avodart both cause impotence. My boyfriend is on Proscar and recently said he would rather have a backrub than sex! He used to worship me and now we are just pen pals. He still seems to like me but there is no sexual component.

“According to his doctor, my friend has the smallest prostate he’s ever seen. Why do the doctors want to shrink it to nothing? Is it sex or death? If I had a choice like that to make, I’d go for sex. I’m only 74 and he is younger.

“I have heard that it is possible for healthy people to have sex for life. Maybe some men are too embarrassed to discuss this subject with their doctor. I still think there should be a way to get around this side effect. Would it help if he didn’t take the pill for the weekend?”

At the time we received this question we knew that both Avodart and Proscar could reduce libido and contribute to erectile dysfunction. We did not know, however, that such side effects might be long lasting. We responded that it was not clear that a “drug holiday” on weekends would restore his sex drive. We suggested that a lower dose might solve the libido problem and still protect his prostate. We now know that might not have been the case since the low-dose Propecia pill (one fifth the Proscar dose) can still cause problems.

The official prescribing information that comes with Propecia suggests that sexual side effects disappear after the drug is discontinued and “in most of those who continued therapy.” But in April of 2011 the FDA added that erectile dysfunction, libido disorders, ejaculation disorders and orgasm disorders might continue “after discontinuation of treatment.”

Research now confirms this possibility and raises some disturbing new questions. Michael Irwig, MD, just published a paper in the Journal of Sexual Medicine (online, July 12, 2012) titled, “Persistent Sexual Side Effects of Finasteride: Could They Be Permanent?” Dr. Irwig recruited over 50 otherwise young (average age 31) and healthy men to his study. They had complained about sexual dysfunction on a website ( None had sexual problems before taking Propecia for male pattern baldness. After taking the drug they all had sexual side effects “which persisted at least 3 months despite cessation of the medication.”

Dr. Irwig interviewed them and reassessed their situation over a year later:

“In a group of 54 otherwise healthy former users of finasteride who developed persistent sexual side effects that lasted at least 3 months, 96% continued to experience these effects when reassessed 9-16 months (mean 14 months) later, raising the possibility of permanent effects.”

These men complained of the following side effects:

• Reduced sex drive, lowered libido
• Reduced sexual arousal
• Erectile Dysfunction
• Fewer spontaneous erections
• Impaired orgasm, reduced orgasmic satisfaction
• Reduced sensation
• Reduced penis size, diministed testicular size
• Decreased ejaculate volume
• Curvature of the penis
• Testicular pain
• Prostatitis
• Depression
• “Disconnection between the mental and physical aspects of sexual function”

The idea that finasteride might cause permanent sexual dysfunction comes as a great shock to physicians and patients, especially for a drug that is prescribed for cosmetic purposes (hair loss). Animal research confirms that finasteride and a related compound called dutasteride (Avodart) might have long-term negative sexual consequences.

Prescribers often assume that drug side effects go away when a drug is discontinued. We have learned the hard way, however, that some drugs cause permanent complications. The heartburn medicine metoclopramide (Reglan) can cause a kind of brain damage called tardive dyskinesia that leads to uncontrollable muscle movements. It took the FDA decades to put a black box warning in the prescribing information warning doctors that this side effect can be irreversible and that “treatment with metoclopramide for longer than 12 weeks should be avoided in all but rare cases where therapeutic benefit is thought to outweigh the risk of developing tardive dyskinesia.”

There are other examples where drug side effects can persist long after a medication is stopped. Some people are so susceptible to statin-type cholesterol-lowering drugs (atorvastatin, lovastatin, simvastatin, etc) that muscle pain, weakness and mental fogginess may persist for months or longer after the drugs are discontinued.

So what are we to learn about the Propecia problem? Here are some things to consider:

• Clinical trials do not always reveal how common or serious drug side effects may be.
• Some people may be more susceptible to adverse drug reactions than others.
• Drug complications can sometimes persist long after a drug is discontinued.
• Always weigh the benefits and risks of any medicine before starting down what may be a long, lonesome road.

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  1. Tom

    Finesteride/Proscar has not been kind to me. I have an enlarged prostate and must get up two to four times a night.
    In 2003 my doctor prescribed Proscar (5mg daily). It didn’t change my nocturnal visits, but the good doctor assured me it was keeping things from getting worse.
    By 2010 I was experiencing minimal libido, ED and what I later learned was called Peyreonie’s Disease (bent penis).
    As I was in my seventies, I assumed it was the cost of old age. This February I discovered some web sites describing the effects of finesteride and I stopped cold turkey.
    Well, my nocturnal visits haven’t changed, I am rediscovering my libido, but I guess I will be blessed with Peyreonie’s for the rest of my days.

  2. Maureen

    Unfortunately, not all men are willing to admit that they have sexual problems. It’s difficult to cure a disorder without the acceptance of the person involved.

  3. tutorjb1

    Hello. I very clearly remember several months to a year ago that the People’s Pharmacy (and/or perhaps other NPR programs) discussed prostate cancer and some medical organization (Abbrev. with 4 letters) made up of family practitioners, internists, gynecologists and a couple other specialties had conducted two large studies that showed that prostate cancer is so slow-growing that one will surely die of something else before the prostate cancer gets you. I don’t know how much one is likely (or not likely) to suffer before the prostate cancer doesn’t kill you, however, and, of course, urologists are up in arms over the results.
    My mother was a public school teacher her entire life so I underwent complete physicals every year, including being seen by a urologist and it’s a travesty how they would frighten patients or their parents about nothing and then “attack” with their tubes and bars. And they’re adverse to anesthetic, even when I requested it.
    The last two words of that four letter organization are Task Force. It recommended against PSA tests. I’ll never submit to one. I plan to wait for urologists to get their “science” in order or at least until they come to believe in anesthesiology before ever seeing one again.
    I hope that helps. Gives you something to talk about anyway.

  4. tutorjb1

    Yeah. Who IS Dr. Don? Is he a real M.D. or Ph.D. or not?

  5. Jefferson B.

    Who is Dr. Don?

  6. mosebolatan

    Thanks for the information.

  7. SM

    My 72 year old husband has taken both tamsulosin and finasteride for a number of years. He has experienced all these negative side effects, but hasn’t stopped taking the drugs for fear of getting prostate cancer. I’d love to hear alternatives if someone has any to offer!

  8. MSM

    Drugs that cause impotency …. I did not see any mention of a great workaround … the pump.
    I found it works just fine, as a matter of fact it makes me feel like a teenager again.
    MSM age 77.

  9. JGC

    Amen, Dr. Don

  10. Linda

    This sounds like a response from someone who works for Merck.

  11. JMF

    This article leaves no alternative suggestions for BPH.
    There are actually a couple of alternatives. Alpha blockers are frequently prescribed. These drugs can ease symptoms. Ask your physician about drugs such as Flomax (tamsulosin).
    The FDA recently approved Cialis (yes, the drug you see advertised for erectile dysfunction) for BPH. Trouble is that most insurance companies do not want to pay for this FDA-approved use. Your doctor would likely have to intervene on your behalf were you to want to give it a try.

  12. Anna

    When I first began reading about saw palmetto for prevention or treatment of prostate problems sometime back in the 1980s, I recall reading that tests (at that time anyway) showed that it compared favorably with proscar and had analogous effects on DHT. If this is true, does saw palmetto have the same side effects as Proscar as described in the article?

  13. Jefferson B.

    Thank You, Peoples’ Pharmacy! This article covers several areas that I, for one, was not likely to ask my doctor or investigate and the sort of things I don’t believe most doctors would mention to patients, This is exactly the information we need from a reliable source like The Peoples’ Pharmacy.
    I take a lot of Meds to treat some very serious conditions and who knew that side effects (that I’m lucky not to suffer) could continue after stopping a drug completely? It will cause me to examine possible side effects much more closely in the future.
    More and more, I find myself relying jointly on The Peoples’ Pharmacy and Consumer Reports for the information I wish my doctor would tell me, but can’t count on him to do so.
    Thank you very much,
    JB – tutorjb1

  14. ab

    My husband started taking this medicine at age 78 – he is now 88.
    He has an excellent sex drive with complete functionality. We have intercourse to ejaculation a couple of times a week, in addition to oral sex to climax.
    So, after ten years of taking this medicine, he has a beautiful head of hair which helps avoid skin cancer and he has had no adverse reactions.
    Perhaps younger men have other estrogen exposures or food/beverage/lifestyle behaviors which might change the metabolism of the propecia?
    Perhaps some men were more “feminine” hormonally prior to beginning propecia, and the medicine simply enhanced what was already happening?
    Perhaps the men in the study were low T?

  15. Barbara

    For 30 years Merck got away with harming patients with Propecia. How many other drugs are doing the same thing, causing terrible side effects and patients are not told?
    A drug dealer is a drug dealer!

  16. Dr. Don S.

    A lesson to be learned. On the surface many innate body functions appear to be unnecessary, and therefore we rush in to “tinker” with it to get a desired result as in blocking the conversion of testosterone to DHT. Our body was crafted by a Designer and Creator with infinite intelligence. When we alter anything, we are just asking for trouble.

  17. Ken

    How long are we going to allow these chemical and/or manufacturing companies to experiment with us as their test subjects? It appears that “rigorous” testing by folks making drugs, artificial sweeteners, and Roundup resistant crops is minimal at best.

  18. Viki H.

    This was a great article. I am a hair stylist and get a lot of questions about these treatments from my follicle deprived clients. Thank so much.

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