Like all medicines, Propecia/Finasteride can cause side effects, although not everybody gets them. Most of the effects are mild or moderate.
Stop taking Propecia/Finasteride and talk to your doctor if you experience:
- Symptoms of an allergic reaction, such as swelling of your lips, face, tongue and throat; difficulty swallowing; lumps under your skin (hives) and breathing difficulties
You should also promptly report to your doctor if you notice any changes in your breast tissue such as lumps, pain, enlargement or nipple discharge as these may be signs of a serious condition, such as breast cancer
Uncommon: may affect up to 1 in 100 users
- you may be unable to have an erection (impotence)
- you may have less desire to have sex
- you may have problems with ejaculation, for example a decrease in the amount of semen released during sex. This decrease in the amount of semen does not appear to affect normal sexual function.
- breast swelling or tenderness
- palpitations (feeling your heartbeat)
- changes in the way your liver is working, which can be shown by a blood test
- pain in the testicles
- blood in semen
- persistent difficulty having an erection after discontinuation of treatment
- persistent decrease in sex drive after discontinuation of treatment
- persistent problems with ejaculation after discontinuation of treatment
- male infertility and/or poor quality of semen
If any of these side effects become serious, or if you notice any side effects which are not listed, please tell our doctors. It will be helpful if you make a note of what happened, when it started and how long it lasted.