Propecia Side Effects
Propeciasideeffects.com was formed to spread the word about the under-recognised, potentially irreversible side effects caused by taking Propecia (finasteride) 1 mg each day. A number of men have suffered erectile dysfunction, impotence, low libido and gynaecomastia after using Propecia.
The shattering truth for these men is that the side effects did not disappear after they stopped taking finasteride. Years later these individuals are still suffering in silence, with a seriously reduced quality of life due to erectile dysfunction and impotence. It is not known exactly what causes these changes, or how to screen people before treatment.
The purpose of this site is to inform others considering using Propecia.
Thinking of using Propecia? Can you imagine a life with a seriously reduced ability to get and keep an erection? Read on. You may want to think again.
What is post-finasteride syndrome (PFS)?
Post-finasteride syndrome (PFS) is the name given to sexual, mental and physical side effects that carry on after a man stops taking finasteride. Finasteride is sold as Propecia for hair loss, and as Proscar for an enlarged prostate.
The symptoms most often reported include erectile dysfunction, low libido, reduced sensation, depression, anxiety, and problems with memory and concentration. In some men they last for years.
No one yet knows how many men are affected, why it happens to some and not others, or how to treat it. In 2024 the UK medicines regulator, the MHRA, warned that sexual side effects of finasteride may persist after treatment is stopped.
Epigenetic = lasting damage
Why do side effects carry on long after the last tablet? Researchers now suspect epigenetics: chemical tags on DNA that switch genes on or off without changing the DNA itself. These tags are copied each time a cell divides, so a change triggered by finasteride could last long after the drug has gone.
In a 2019 study, the gene that makes 5-alpha reductase, the enzyme finasteride blocks, carried tags that switch it off in the nervous system of more than half the men with post-finasteride syndrome who were tested.
The studies are still small, and no treatment has yet been shown to reverse these changes.
Melcangi et al., Endocrine Connections, 2019
What the medicines regulators now say
Since this site was first written, regulators in the US and the UK have strengthened their warnings about finasteride, including the risk of side effects that persist after stopping it.
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The US Food and Drug Administration (FDA) required Propecia's label to include sexual side effects, such as problems with libido, ejaculation and orgasm, that continued in some men after they stopped taking the drug.
ABC News report on the FDA label change -
The UK Medicines and Healthcare products Regulatory Agency (MHRA) warned that finasteride is linked to sexual dysfunction that may persist after treatment is stopped, and to depression and suicidal thoughts. Patient alert cards were introduced in finasteride packs.
MHRA Drug Safety Update on GOV.UK -
After a further review, the MHRA strengthened the finasteride 1 mg warnings again, noting that sexual dysfunction may contribute to mood disorders.
MHRA announcement on GOV.UK
Read on
- My storyHow five and a half months on Propecia led to years of side effects, and three doctors who didn't believe me.
- EpigeneticsWhy the changes may last after you stop taking finasteride, and what the research has found so far.
- VideosTwo short films about permanent side effects of Propecia and finasteride.
- News and forumsThe latest news, and a discussion forum for men living with post-finasteride syndrome.