Sounds like 'fin-AS-ter-ide'

Finasteride is used to treat symptoms of an enlarged prostate. Find out how to take it safely and possible side effects. Finasteride is also called Finpro, Fintral or Proscar.

Type of medicine Also called
  • Medicine to treat enlarged prostate 
  • Finpro®
  • Fintral®
  • Proscar®

What is finasteride?

  • Finasteride is used to shrink an enlarged prostate and in this way helps to relieve the symptoms associated with an enlarged prostate such as difficulty in beginning the flow of urine, weak urinary flow, and the need to urinate frequently or urgently (including during the middle of the night).
  • It is also prescribed for hair loss in men, but this is not subsidised in New Zealand.  
  • Finasteride is available as tablets.


  • The dose of finasteride for enlarged prostate is 5 milligrams once a day.
  • A lower dose of 1 milligram once a day is used for hair loss in men. 
  • Always take your finasteride exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much finasteride to take, how often to take it, and any special instructions.

How to take finasteride

  • Take finasteride tablets with a glass of water at the same time each day.
  • You can take finasteride with or without food.
  • To reduce your urinary symptoms, you must keep taking finasteride every day. Your symptoms may start to improve within a few weeks, but it can take 6 to 12 months to notice a benefit.
  • If you forget your dose, take it as soon as you remember that day. But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.

Special instructions

Finasteride may cause harm to an unborn baby. 

  • It is recommended that you use a barrier method of contraception (such as a condom) if your partner could become pregnant.
  • Women who are pregnant should not handle the tablets.

Side effects

Like all medicines, finasteride can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Side effects What should I do?
  • Less desire for sex and problems having an erection (decreased libido)
  • Tell your doctor if troublesome.
  • Swollen breasts, lumps in your breasts, pain or discharge from the nipples
  • Tell your doctor if troublesome.

  • Mood changes, anxiety, depression, or worsening depression, low mood, aggressive tendencies, thoughts or talk of suicide and self-harm.
  • If you experience any of these symptoms, tell your doctor immediately or ring Healthline on 0800 611 116


When certain medications are taken together, an unintended reaction may occur – this is known as an interaction. Finasteride may interact with a few medications and herbal supplements, so check with your doctor or pharmacist.

Learn more

If you have any questions about your medicines or about the combination of medicines that you are taking, or if you are concerned about any side effects or interactions talk to your pharmacist or doctor.

The following links provide further information on finasteride. Be aware that websites from other countries may contain information that differs from New Zealand recommendations.

Finasteride Patient Info (UK)

Credits: Sandra Ponen, Pharmacist. Reviewed By: Nicola Rowbottom, Pharmacist, South Canterbury Last reviewed: 09 Jan 2017