My Comments - This is a well thought out study and does
demonstrate penile changes in rats that were given finasteride over
a very short time frame.  What this has to do with Peyronies Disease
is not evident.  The allegation that finasateride shrinks the penis is
not all that convincing from this study.  Technically, this is true as the
Corpus Cavernosum is part of the penis, but how it affects the
overall size of the penis, particularly the erect size, is not clear.
Further, when these rats were given finasteride and then
testosterone, the shrinkage was much less. Is there some mechanism
by which a decreased Corpus Cavernosum possibly increases
pressure on the Tunica resulting in scarring AKA Peyronies?  An
unanswered question.

My reader feedback indicates that a fair number of people in the
medical profession read this site.  Looking at the tissue samples
of the Tunica Albuginea, i.e., control vs given finasteride, they look
Any medical professionals out there who read this site,
please tell me what you think of the 2 tissue samples.

Does this study demonstrate that finasteride and Peyronies Disease
are linked?  No abnormalities noted in the Tunica Albuginea.  I
would give it a
Grade D.

ULTRASTRUCTURE - Asian Journal of Andrology March 2003

Once again, an important study on this issue, not from the
United States, but from China.  This is an extremely small study
and not on humans, but laboratory rats.  However, if these
results could be replicated on a larger human male group, this
would be pretty close to a smoking gun linking finasteride to
Peyronies Disease. Of course, this would require a leap of logic
finding that the results in 18 rats are also applicable to a large
scale group of human males.

  • Eighteen 9 week old male rats were divided in 3 equal groups.
    Group 1 - control  Group 2 - castrated  Group 3 - were given
    finasteride for a 4 week period and then sacrificed

  • The thickness of the Tunica Albuginea was significantly reduced
    in Group 2, but there was no significant difference between
    Group 1 and Group 3

  • Group 1 had the elastic fibers in the Tunica Albuginea very thick
    and regularly arranged.  Group 3 did not have regularly
    arranged fibers and they were replaced by thick and irregularly
    arranged collagenous fibers. AKA Peyronies Disease

  • The Corpus Cavernosum in Group 1, the muscle fibers were rich
    and contained few elastic and collangenous fibers. In contrast,
    in Group 3 there was a considerable amount of irregularly and
    thick irregularly arranged collangenous fibers

This is a really small study and I was surprised that there were no
photos of the tissue samples in the report. However, here are some
photos from my files that illustrate the difference between healthy
penis tissue and Peyronies:

Elastin in normal tissue with loose network of fibers extending in
all directions; this permits stretch and contraction of penile tissue in
nearly any direction.

Elastin in Peyroine's Disease: Note that the fibers are reduced in
number and the fibers that are present are very short and
abnormal.  This tissue would not stretch normally.

Although there are many limitations, the grade I would give this  
study as proof there is a link between taking finasteride and
developing Peyronies Disease is Grade

There is an excellent website by the name of
ehealthme.  They use
various methods to collect data on drugs and their effects. I have
reprinted a very limited amount of their data concerning finasteride
and Peyronies Disease.

This is a review of Peyronie's disease by studying 4,979 people who
take Finasteride. We analyze: the time on Finasteride when people
have Peyronie's disease, age of these people, the severity of
Peyronie's disease, how they recovered, and common conditions and
drugs used besides Finasteride. The review is created by eHealthMe
based on reports from FDA and social media, and is updated

For patients like me, how are my drugs? On eHealthMe, you can
research 300 million drug outcomes from FDA and social media since
1977. The results are personalized to your gender and age. Start now

Finasteride (latest outcomes) has active ingredients of finasteride. It
is often used in enlarged prostate, hair loss. Commonly reported side
effects of Finasteride include fatigue, dizziness, fatigue aggravated,
weakness, dyspnoea exacerbated.

Peyronie's disease

Peyronie's disease (bent penis) has been reported by people with
erection problems, high blood pressure, depression, high blood
cholesterol, hypothyroidism.

As of Dec, 23, 2013: 4,970 people reported to have side effects
when taking Finasteride. Among them, 6 people (0.12%)

have Peyronie's Disease.

Finasteride may or may not be related to the development
of Peyronies Disease.  Based on the evidence I have
reviewed there is simply not enough evidence to establish
even a weak cause and effect relationship between the