Note: This post comes from one of our favorite readers (he has requested to remain anonymous), who has contributed posts in the past about FDA and clinical trial issues. Some of his previous contributions are here, here, here, and here.

He has broken down the latest finasteride side effect study for our readers and explains why interpreting the data is problematic:

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This month an article appeared in a medical journal (Irwig MS. Journal of Sexual Medicine, 2012 Epub ahead of print) that relates to persistent sexual side effects of finasteride and has generated discussion in your blog from both posters and commenters. An abstract of the paper can be found at: Persistent Sexual Side Effects of Finasteride: Could They Be Permanent?

I am a physician scientist (MD-PhD) who spent over 20 years conducting clinical trials and interpreting clinical data. Because I believe this is an important issue, I wish to summarize this study (and discuss its strengths and limitations) for your readers. Two biases that I am disclosing: (1) I believe that persistent sexual side effects of finasteride exist, and (2) I also believe that well-done published scientific investigations on this phenomenon are lacking and readers (most who are unfamiliar with scientific investigations) historically come to form impressions from magazine and newspaper articles, lawyer-run web sites, and blogs… none of which are ideal to better define and understand this phenomenon.

Method:
Fifty-four men were recruited. Most men (undefined number) were recruited from an internet site that focuses on sexual side effects from Propecia. Other men (number undefined) were recruited from the author’s clinical practice. To participate in the study, all men were required to have had their finasteride use before age 40 and (by their self-report) and have no history of sexual dysfunction, medication use (other than antibiotics), or significant medical or psychiatric conditions at the time that they began taking finasteride. Initial information for the study was collected by telephone or Skype. Info on sexual dysfunction, medication use, significant medical or psychiatric conditions, etc before and after finasteride use was collected. Follow-up emails were sent to the participants 9-16 months after initial interview (average 14 months). Multiple valid questionnaire scales of sexual dysfunction were used.
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I started taking 1.25 mg of proscar everyday for hair loss and noticed side effects. I took the medicine for four days and experienced nipple sensitivity, erectile dysfunction, and a cold tingling sensation in my penis. I’ve stopped taking the drug and am very concerned because of recent news reports of permanent side effects. Could taking such a small amount really cause permanent problems? Or am I too paranoid and do you think the side effects will resolve in the next couple weeks. It’s been 4 days since I quit proscar.

I think you’re probably being paranoid, but talk to your prescribing doctor about changing the dosage or stopping the medication completely.

In your case, I would worry about the power of suggestion being responsible for these side effects more so than the medication, but if you are concerned you can make the decision not to take it.

I have been taking Propecia since I was 28, in varying doses from .25mg to 1mg. I have seen a huge benefit from it, but I have also seen some increase in breast tissue along with some pain in the breast area. My doctor has asked me to stop taking it to see if the pain subsides, and I have stopped for about a month but it has made little difference in terms of pain. What has changed is that my hair has thinned dramatically, mostly in the crown area.

My doctor would like me to continue off of Propecia for another month or so to rule it out as a culprit, but I’m concerned that I may lose a lot of hair permanently. Can you give me any idea of how permanent the hair loss is that I am experiencing now? If I’m off Propecia for two months, am I likely not to get back to near the same levels of hair that I had while I was on it?

If you were my patient, I would probably tell you to stay on the Propecia (unless you are willing to lose your hair and then not get it back). Hair lost after stopping Propecia might regrow for some, but I would expect that once the hair is gone, it won’t return.

Breast enlargement resulting from Propecia does not go away simply by stopping the drug. The breast tissue should be treated by a person knowledgeable in this field, first examined carefully to make sure that there is no breast cancer. Then consider treating it as a typical gynecomastia case with surgery and possibly liposuction done by someone experienced.

I am now working with such an experienced doctor at my office who treats this condition, which can occur with or without Propecia use.

Snippet from the article published online June 20, 2012:

Finasteride use marginally increased the incidence of prostate and overall cancer at a level of statistical significance. Dutasteride use significantly increased kidney cancer risk. Dosage analysis showed that lower doses of finasteride were associated with higher overall and prostate cancer risks.
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The major limitation is the lack of important data in the NHIRD, such as prostate cancer histologic grades, smoking habits, alcohol consumption, body mass index, socioeconomic status, and family history of cancer.

Read the rest at The Oncologist — A Population-Based Nested Case-Control Study in Taiwan: Use of 5α-Reductase Inhibitors Did Not Decrease Prostate Cancer Risk in Patients with Benign Prostate Hyperplasia

This study seems to go against the grain of some of the original studies which showed some protective effect of finasteride in the overall population, however, the original study used the 5mg dose. This article suggests that the results of lower doses might be a problem.

I know I’m going to get a bunch of questions about this one, but I can not comment beyond what is in the article. I’m just presenting it so you’re informed.

After about ten years of being on Propecia/finasteride I quit four months ago. Before I quit I felt my side effects were minimal: a little anxiety, reduced ejaculate output, loss of morning erections, and some reduced erection stamina. After I quit (cold turkey with assurance from two urologists I would bounce back virtually immediately), I felt a substantial change, specifically a reduction or elimination of side effects. Admittedly it took a scary, long road to get here.

However, despite all of that, the significant hairloss I have suffered has made me regret my decision. I want to go back on but only if I’ll likely regrow what hair I lost or at least increase the density of the hair I have. What do you think I should do? Should I resume the finasteride at a different dosage? Different amounts a week (i.e. once every other day)?

You should talk to your prescribing doctor. I don’t know your medical history and this is a prescription medication. It’s possible a reduction of the dose may provide some benefit and eliminating the side effects, but this is something you and your doctor should discuss.

You needed a good Master Plan before you started it, when you stopped it, and now with the decisions before you, again you need it more than ever. Your doctor should help you with this Master Plan for your future management.

Doc

Bad reaction to Rogaine foam.. 5% PG formulas cause irritation. If I mixed 2% and 5% together in the same bottle would that be a problem?
The goal would be to get something a little stronger than 2% but less irritating that full 5%.

Thanks

Mixing the two liquid formulas of different strengths should not produce problems. Hopefully it will provide you with some results and less irritation. Good luck and let us know how it works out.