Bernstein Medical - Center for Hair Restoration - Propecia Persistent Side Effects
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Recent news reports, coupled with warnings from Merck and the FDA, about Propecia’s possible persistent sexual side effects have caused growing concern about this popular hair loss treatment. An increasing number of men now fear that Propecia (finasteride 1mg) will cause permanent sexual dysfunction.

Merck’s and the FDA’s warning, however, was based on a small number of random self-reports, not on empirical studies that showed a cause and effect relationship between finasteride and sexual dysfunction. There are two possible reasons that existing studies have not found a significant relationship between finasteride use and persistent sexual dysfunction: 1) the effect of finasteride on sexual function is too small to significantly measure in any one study, or 2) finasteride has no significant negative effect on sexual function.

To address the first possibility, Aditya K Gupta and Andrew Charrette ((Gupta AK, Charrette A. The efficacy and safety of 5α-reductase inhibitors in androgenetic alopecia: a network meta-analysis and benefit-risk assessment of finasteride and dutasteride. J Dermatolog Treat. 2014;25(2):156-61.)) at the University of Toronto recently conducted a large scale meta-analysis across 16 controlled studies, studies designed to test the efficacy of finasteride, to see if a significant number of patients in those studies reported persistent sexual side effects. The rationale of a meta-analysis is that if there is an effect (of finasteride on sexual function) that is too small to measure in any one particular study, then it may be possible to detect the effect if one pools data from many different studies.

Gupta and Charrette analyzed the results of 16 studies that compared various doses of finasteride against a placebo and found that finasteride consistently proved effective in stopping or slowing hair loss. They also found that the number of self-reported cases of persistent sexual dysfunction by patients given finasteride was statistically no different from the number reported by patients given a placebo.

In other words, they found that finasteride was no more likely to cause persistent sexual dysfunction than a placebo.

This study supports the conclusion of existing literature that there is no correlation between finasteride use and persistent or permanent sexual dysfunction. That said, this is an important issue that still needs to be studied.

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Q: As a Propecia user, I was alarmed when I read headlines last year about a new study indicating very high rates of depression and erectile dysfunction caused by Propecia, with symptoms persisting even after the drug was stopped. However, when I read the articles, this “study” appeared to be survey of 61 men who had taken Propecia and already reported sexual problems who were then asked about symptoms of depression. These rates of depression were compared to a small survey of men who had hair loss but had never taken Propecia.

Anyone with a basic understanding of statistics would know such a survey was deeply flawed. First, it is a textbook example of a bad data sample — to get sound results you have to start with an unbiased and random group of people who took the drug, not a self-selected group of men already suffering symptoms. The study also confuses correlation with causation — because these men are suffering from ED or depression does not necessarily mean it was caused by the drug. Am I missing something here, or did the media just report these “findings” with no scrutiny on what was actually studied? — Jonathan, Brooklyn, NY

A: Jonathan, I think you’re right on the mark. The way the study was conducted raises a lot of concern about the accuracy of the findings. It is really important that additional data is obtained in a controlled way, as this will be most useful for physicians in advising patients. I addressed concern on these reports last year. The issue of persistent sexual dysfunction as a side-effect of finasteride (Post-Finasteride Syndrome) is an on-going issue that we take very seriously. I sit on the International Society of Hair Restoration Surgery (ISHRS) Task Force on Finasteride Adverse Events, so this is an issue that we watch very closely.

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Q: I have heard that side effects from finasteride can persist even after stopping the medication. What is the most current information on this issue? — S.V., Short Hills, N.J.

A: For the past two years I have been on the International Society for Hair Restoration Surgery (ISHRS) Task Force on Finasteride Adverse Events and struggling to make sense of this issue. There seems to be a disconnect between the relatively low incidence of side effects that we, as physicians, see in our practices, what published controlled studies have shown, and what is now being reported on the internet and in some instances in the media. For example, a 2012 study by Sato of 3,177 Japanese men published the Journal of Dermatology, showed a 0.7% incidence of adverse reactions to finasteride 1mg and no persistent side effects after stopping the medication.

That said, there has been a recent increase in anecdotal reports of side effects from finasteride as well as reports of persistent side effects after the medication has been discontinued (referred to as “Post-finasteride Syndrome”).

The FDA

Based on post-marketing reports of sexual dysfunction, in April 2012, the FDA announced changes to Propecia (finasteride 1 mg) labeling to expand the list of sexual adverse events and that some of these events had been reported to continue after the drug is no longer being used. It is important to note that no new clinical studies were reviewed to evaluate these adverse events and that the FDA is not aware of any additional controlled clinical studies conducted to evaluate these adverse events or to determine their cause or duration. (see FDA Label Changes for Finasteride 2012)

The FDA states that despite the fact that clear causal links between finasteride (Propecia and Proscar) and sexual adverse events have NOT been established, the cases suggest a broader range of adverse effects than previously reported in patients taking these drugs. The FDA states that it believes that finasteride remains a safe and effective drug for its approved indications, but also advises that healthcare professionals and patients should consider this new label information when deciding the best treatment option.

The difficulty with interpreting anecdotal information is significant. The following need to be considered; first, sexual dysfunction, both temporary and persistent, is quite common in the general population and patients may have new-onset sexual dysfunction from some other, unrelated, cause and second, patients may have real (physiologic) side effects from the medication and then have psychological after effects. It is so difficult to sort these factors out.

The ISHRS

The Finasteride Symposium at the 2012 ISHRS, of which I was a panelist, explored safety issues with finasteride. Dr. Akio Sato presented his data (quoted above) suggesting that finasteride side effects are uncommon and that persistent side effects were not seen. Dr. Freedland, a urologist and featured guest speaker at the ISHRS symposium, questioned whether long-term effects of a slight elevation in estrogen levels could have adverse effects on the prostate. The panel discussed the paper of Dr. Michael Irwig at George Washington University that appeared in The Journal of Sexual Medicine this year. In his survey of 54 patients of men who had persistent sexual side effects three or more months after the discontinuation of finasteride, he reported that sexual dysfunction continued for many months or years in the majority of the patients.

Difficulties in interpreting this study are that it assumed that the patient’s sexual dysfunction were caused by finasteride when, in fact, there is no way of knowing that finasteride was the actual cause of the side effects (this would need a blinded, placebo-controlled study). A second reason that makes interpretation difficult is that, because there was selection bias in the Irwig survey, there is no way of knowing if these patients are representative of the population of men on finasteride. That said, the data presented by Dr. Irwig stresses the importance of having more clarity on the potential side effects of finasteride, since it is so widely prescribed.

It was clear from the presentations and questions asked, that many issues are still unresolved. All in attendance agreed that further research is urgently needed. In the short term, it is most important that all patients who are having problems can have easy access to doctors with expertise in this area, so that they can be diagnosed properly and treated.

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Q: Dr. Bernstein, I am an attending at Mass General Hospital in Boston and would like to ask you regarding your experiences using finasteride for male androgenetic alopecia. While I have not noticed any side effects in the patients that I have been treating, I increasingly get questions regarding side effects based on the recent media attention to reports of potentially permanent problems regarding libido or erectile dysfunction. I know that in the literature there is a slight increase of reversible sexual dysfunction (~4% vs. ~2% in placebo) with Propecia, and no convincing evidence to date in the medical literature that have used controlled studies regarding permanent problems even after discontinuing Propecia. — S.Z., Boston, Massachusetts

A: That is correct.

Q: I know that you have treated many patients over a long period of time, and I was thus wondering what your take is on potentially permanent sexual dysfunction after taking finasteride. Have you seen any convincing reports/patients or do you have any concerns regarding irreversible side effects?

A: I have seen 5 cases in over 10,000 patients on finasteride that complained of this but, of course, there is no way to know for sure if there is a cause and effect relationship. As you know, real side effects may be followed by psychological ones and if the sexual dysfunction has another cause, then stopping finasteride would have no effect on the symptoms. The incidence of intermittent or persistent sexual dysfunction in the general population of men is about 30%, so one would expect these numbers to be much higher just due to the normal incidence. It is really a difficult situation to understand. The experience that my colleagues and I have in our practices is much different than one would expect after reading the numerous anecdotal reports on the internet.

Q: Would you think it is safe to say that any potential sexual dysfunction is reversible after discontinuing the use of finasteride?

A: I don’t think that anyone knows at this point. The FDA is coming down on the side of caution and saying that it is possible, although it is not based on any new studies. If the phenomenon is real, the possible mechanism is not yet known.

Q: In the relatively few patients that I have treated with Propecia, they did not even report temporary problems regarding libido or erectile dysfunction. Do you think they are real or rather attributed to Propecia simply because the patient is made aware of these potential side effects?

A: I think that psychological effects may account for many cases. At this time, it is still not clear if a physiologic “post-finasteride syndrome” is real. A lot more work needs to be done before we have a definitive answer to this question.

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Q: I recently visited my dermatologist regarding my hair loss, and after checking my hair he said I am showing signs of Androgenetic Alopecia (common baldness), and said if I don’t treat it, it will progress. From my research on the net, I figured he will put me on Propecia. In fact he put me on Avodart. When I told him it is not FDA-approved for hair loss, and Propecia is, he said Avodart is better and brings DHT down more, and Propecia is nothing next to Avodart. He told me to take it every day for 2 weeks, then every other day from then on as it has a long half life. From researching on the net, many hair restoration doctors rarely prescribe Avodart for hair loss due to some dangers. What is your opinion on this? — T.G., Darien, Connecticut

A: Although dutasteride (Avodart) can be more effective for male pattern hair loss, I would start with finasteride (Propecia) as many patients do great with it and the safety profile is better. The following are things I would consider before starting dutasteride:

  1. As you point out, dutasteride is not FDA-approved for hair loss.
  2. There is no data on its safety when used for hair loss. This is important since dutasteride has been only tested on an older population of patients (with prostate disease) rather than a younger population of patients needing medical treatment for androgenetic alopecia.
  3. These is no natural model for dutasteride’s combined blockage of both type 1 and 2 5-alpha reductase (finasteride blocks only type 2 5-AR and there are families that have this deficiency and have no long-term problems. This, by the way, is how the drug was discovered).
  4. The type 1 enzyme which dutasteride blocks is present in many more tissues of the body (including the brain) compared to type 2 (which is more localized to the skin).
  5. Although so far unproven, there is a concern that finasteride may produce side effects than can be persistent after stopping the medication (post-finasteride syndrome). It this does turn out to be true, the effects from dutasteride would most likely be significantly more persistent.
  6. If you start with finasteride and do have side effects, you will most surely have side effects from dutasteride; therefore, by taking finasteride first you will have avoided the potentially more problematic side effects from dutasteride
  7. You may respond well to finasteride, and so do not need to consider dutasteride
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Led by Dr. A. Sato, a Japanese team of medical researchers published the largest finasteride study ever performed, “Evaluation of efficacy and safety of finasteride 1mg in 3,177 Japanese men with androgenetic alopecia.” It investigated the effects of finasteride over a 3 1/2 year period in men with androgenetic alopecia, or common baldness.

The study found that patients who had experienced hair loss for an extended period of time and were treated with finasteride exhibited notable hair growth. While a fairly small proportion of patients with a hair loss duration over 10 years exhibited “greatly increased” growth, 85% of patients with hair loss duration of more than 15 years experienced “moderate” or “slightly increased” growth. Physicians have thought that people with advanced hair loss do not respond as well as patients in the early stages of hair loss. However, in light of the results of this study, that determination should be reconsidered.

Further, the same study found that the initial age of a hair loss patient at the time of commencing treatment has little to no effect on the outcome. While the efficacy studies that are included in the Propecia package insert were conducted in men 18 to 41 years old, men over 41 appear to respond as well as the younger group. Adverse reactions occurred in only 0.7% of the study population and the Sato study found no increase in adverse safety events over time.

In summary, the Sato study showed an increased response rate to finasteride 1mg with increasing duration of treatment. In addition, it is effective in a larger portion of the male population with androgenetic alopecia than previously thought.

Reference:

Sato A, Takeda A. Evaluation of efficacy and safety of finasteride 1mg in 3,177 Japanese men with androgenetic alopecia. J Dermatol 2012; 39: 27–32.

Download the Sato study on finasteride

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Q: You prescribed Propecia for my hair loss. I was wondering if the news report on Propecia side effects has altered your opinion regarding the safety of this drug? — N.D., Belle Meade, Tennessee

A: It has not changed. I believe you are referring to Dr. Michael Irwig’s study at George Washington University published in the Journal of Sexual Medicine. I was already aware of the study when I prescribed the medication for you and we discussed the risk of persistent side effects at your consult.

Although all types of data should be considered, it is important to realize that this was not a scientific study, but a survey. It had very significant selection bias. From this type of study, one can’t prove cause and effect relationships or even get a sense of actual incidences. These were patients who were recruited because they already had persistent sexual dysfunction. Since it is not clear if their persistent problems were directly due to the medication or from other factors, and since these patients were selected, rather than randomly assigned, the additional information can be gained from the report is very limited.

That said, the reporting of persistent side effects should not be taken lightly, but should be viewed in the context of all available data. It is extremely important for us to continue to be vigilant, as this is a very significant issue, but it is equally important not to make decisions on data sensationalized in the media. As a result of the finasteride data, some are presenting surgery as a more reasonable alternative than medication. For a young person, that is usually not the case.

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Q: I am 27 years old and I have been on Propecia for 12 months now. Honestly, I have seen no response from it. In my dermatologist’s opinion I am a non-responder. I asked about Avodart and he said, since Propecia didn’t help then Avodart won’t help as well since both are DHT blockers, and if one didn’t work the other won’t either. In your opinion do you think Avodart is better? I have read that it blocks more DHT than Propecia. What is the dosing for Avodart? If someone does not respond to Propecia will they also not respond to Avodart? — A.C., West University Place, Texas

A: Avodart (dutasteride) is more effective than Propecia (finasteride) and some patients will respond to dutasteride who do not respond to finasteride. Dutasteride decreases serum DHT about 90% compared to 70% for finasteride. The usual starting dose of Avodart is 0.5mg a day.

That said, dutasteride is not FDA approved for use in hair loss and if a person has sexual side effects, the side effects are more likely to be persistent after stopping the medication compared to finasteride.

Read more about Avodart (dutasteride)

Read more about Propecia (finasteride)

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Q: I started using both Propecia (finasteride) and Rogaine for roughly the past 15 weeks. In the last month I’ve been experiencing pain in my left testicle area. At first I thought this may be due to Varicocele; however, after some quick internet searches I thought it may also be the Propecia. The pain doesn’t seem to be in the testicle itself as much as the surrounding veins on the left side. What should I do? — B.L., Houston, TX

A: Your symptoms are the classic ones of a varicocele, namely pain on the left side that is adjacent to the testicle. Symptoms of finasteride would more likely be bilateral, although the discomfort does not need to be in the testicle itself. If your symptoms are worse at the end of the day when you have been standing, and less in the AM when you first arise, these suggest a varicocele.

In your pain is consistently worse towards the end of the day, I would see a urologist, as surgical intervention might be warranted, particularly if it is affecting sperm counts – which should be checked as part of the evaluation.

If this is not the case, then stop finasteride for a least a month and see if the symptoms subside. If they do go away off finasteride, I would not take the medication again. If the symptoms persist off finasteride, I would still see a urologist.

Read more about Propecia in our section on hair loss medications.

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