Health Canada enforces product label change for serious muscle-related side effects with finasteride

On June 22 2017, Health Canada reviewed the risk of potential serious muscle-related side effects with finasteride use because of reports in which these events were seen in patients treated with Propecia and Proscar. These included muscle-related adverse events such as rhabdomyolysis (pain in muscles with breakdown of muscle tissue and an increase in certain muscle proteins known as creatine kinase [CK] enzymes, myopathy (disease of muscles with pain and an increase in CK enzymes) and muscle disorders such as pain, weakness, atrophy (wasting) or stiffness.

The full Safety Warning can be found here:

Now, a year later in June 2018, Health Canada has enforced a safety label update, which was recently made to the Canadian product monograph for Proscar and Propecia (finasteride). This label change has now included the following warnings:

  • Rare cases of muscle-related disorders, such as rhabdomyolysis, myopathy, myalgia, myasthenia, and creatine kinase elevation, have been reported in patients treated with finasteride.
  • In some cases, these disorders were found to be reversible with discontinuation of finasteride therapy.

The full warning can be consulted here.


Isotretinoin has also been associated with muscle breakdown, with extreme consequences.

Including one where a patient died:


An article likely related to the new warning on finasteride:

Not sure how they gauge risk of rhabdo and myopathies prior to finasteride treatment?

And more literature showing a high rate of myopathies and elevated CK (“CPK”) during isotretinoin treatment:

One author considers elevated CK a “benign phenomenon”, even when the patients complain of muscle pain. WTF?


Christ, that is horrific.

any news about this topic?
since stopping fin my muscle loss and pain, stiffness still persists and is even getting a bigger issue, since nerves in arms and legs hurt, for this reason unable to sleep during resting and not moving. my t, free t and DHT, also LH is very low. also elevated creatine kinase.
my doc told me to take tamoxifen 20mg/day… anybody has had the same issues? I’ve no idea what to do… is it a neuropathy or cause of low androgens, especially low dht or not working 5ar?

Hello, I have also encountered muscle stiffness problems, especially my right arm and right leg. I feel a little stiffness when I write. How are you now? How long will it take if you recover?, thank you!

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