Finasteride

Sounds like 'fin-AS-ter-ide'

Finasteride is used to treat symptoms of urination (peeing) difficulty in men who have an enlarged prostate. Find out how to take it safely and possible side effects.

What is finasteride?

Finasteride is used to relieve the symptoms of urination (peeing) problems that can happen when you have an enlarged prostate. It works by reducing the size of the prostate.

It can help symptoms of 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).

Read more about enlarged prostate and bladder control problems in men.

It is also prescribed for hair loss in men, but this is not funded in Aotearoa New Zealand which means you have to pay for it.  

Dose

In Aotearoa New Zealand finasteride is available as tablets (1 mg and 5 mg).

  • For an enlarged prostate: The dose is 5 mg once a day
  • For hair loss: The dose is 1 mg once a day.
  • 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.

Precautions before taking finasteride

Finasteride can interact with some medications, herbal supplements and rongoā Māori, so check with your doctor or pharmacist before starting any new products.

How to take finasteride

  • Timing
    • Take finasteride tablets with a glass of water (200-250 mLs)  at the same time each day.
    • You can take finasteride with or without food.
    • Swallow the tablets whole.
  • Take regularly: To reduce your urinary symptoms, you must keep taking finasteride every day.
  • Missed dose: 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.

Note that while your symptoms may start to improve within a few weeks, it can take 6–12 months to notice an improvement. 

Precautions when taking finasteride

Finasteride may cause harm to an unborn baby. 

  • Finasteride is secreted in the semen and it is recommended to use a barrier method of contraception (such as a condom) if your sexual partner is pregnant or likely to become pregnant.
  • Women who are pregnant should not handle the tablets.

Finasteride can interact with some medications, herbal supplements and rongoā Māori, so check with your doctor or pharmacist before starting any new products.

What are the side effects of finasteride?

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 (decreased libido) and problems having an erection (impotence)
  • Tell your doctor if this bothers you.
  • Swollen breasts, lumps in your breasts, pain or discharge from the nipples.
  • Tell your doctor. Cases of male breast cancer have been reported so it’s important to seek help if you have any of these symptoms.
  • 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.
For more information on side effects, see the consumer information leaflets below.

Did you know that you can report a medicine side effect to the Centre for Adverse Reactions Monitoring (CARM)? Report a side effect to a product.

Learn more

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

Finasteride NZ Formulary 
Finasteride Patient Info (UK)
Finasteride MotherToBaby, US
APO-Finasteride 5 for prostate enlargement NPS, AUS (note this brand is not available in NZ)
Profal for hair loss  Consumer Information Sheet, NZ 

References

Finasteride  NZ Formulary 
Dutasteride and finasteride NZ Formulary  
Ricit Medsafe, NZ

Credits: Sandra Ponen, Pharmacist. Reviewed By: Maya Patel, Pharmacist Last reviewed: 04 Feb 2022