Finasteride, a medication to prevent baldness or benign prostatic hyperplasia, known by brand name Propecia and Proscar, slightly raises a man’s risk of developing breast cancer, Health Canada has announced. The Canadian regulatory agency has informed doctors and patients of a labeling update for the medication, which will add safety information.

Finasteride is used for two purposes:

  • Propecia – 1 mg tablets, used for treatment of male pattern hair loss.
  • Proscar – 5 mg tables, used for the treatment and control of benign prostatic hyperplasia – noncancerous enlargement of the prostate.

Finasteride is only used by men.

A small number of men using either formulations of finasteride globally have developed male breast cancer, Health Canada informs. In most cases, the patients had been taking the 5 mg formulation.

Health Canada says that for the moment nobody is sure whether finasteride causes breast cancer, however, it cannot be ruled out either.

In a communiqué, Health Canada wrote:

“The labelling for Propecia, Proscar and several of the generic finasteride products has already been updated to include information on the potential risk of male breast cancer. Updates to the remaining generic drugs will follow.”

Any patient who is on finasteride and notices changes in his breasts should tell his doctor. Changes may include tenderness, nipple discharge, lumps, or breast enlargement.

Written by Christian Nordqvist