Finasteride — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Finasteride?
Finasteride is a 5-alpha-reductase inhibitor used to treat benign prostatic hyperplasia (BPH) and male pattern hair loss (androgenetic alopecia). This medication is commonly prescribed in New Zealand and is funded by Pharmac for BPH (5 mg); not funded for hair loss.
What is Finasteride Used For?
Finasteride 5 mg is used for benign prostatic hyperplasia (BPH) to reduce prostate size and improve urinary symptoms, and to reduce the risk of urinary retention and the need for surgery. Finasteride 1 mg (Propecia®) is used for male pattern baldness.
How Does Finasteride Work?
Finasteride inhibits the enzyme 5-alpha-reductase, which converts testosterone to dihydrotestosterone (DHT) — the androgen responsible for prostate enlargement and hair follicle miniaturisation. By reducing DHT levels, finasteride shrinks the prostate over time and can slow or reverse hair loss.
How to Take Finasteride
For BPH: taken as 5 mg once daily with or without food. Effects on prostate size take 3–6 months to become apparent. For hair loss: 1 mg once daily. Treatment must be continued long-term — effects are reversed within 6–12 months of stopping.
Common Side Effects of Finasteride
- Decreased libido
- Erectile dysfunction
- Reduced ejaculate volume
- Breast tenderness or gynaecomastia (rarely)
- Depressed mood (rare — reported post-marketing)
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Post-finasteride syndrome (controversial — some men report persistent sexual and mood effects after stopping, though causation is debated)
- Rare cases of breast cancer (men)
- Elevated PSA levels masked (finasteride reduces PSA by ~50% — inform your doctor when interpreting PSA tests)
Drug Interactions
Finasteride may interact with other medicines. Always inform your doctor and pharmacist of all medications, supplements, and herbal products you are taking. Key interactions include:
- No major drug interactions documented
- May alter PSA interpretation — inform doctors of use
New Zealand Prescribing Information
Finasteride 5 mg (Proscar® and generics) is funded by Pharmac for BPH. Finasteride 1 mg (Propecia®) for hair loss is not funded and must be purchased privately. Women who are pregnant or may become pregnant should not handle crushed or broken finasteride tablets, as absorption through the skin can cause harm to a male fetus.
Frequently Asked Questions
How long before I see results from finasteride for BPH?
Finasteride takes 3–6 months before a meaningful reduction in prostate size and symptom improvement is seen. It is often combined with an alpha-blocker (such as tamsulosin) for more rapid symptom relief while waiting for the prostate-shrinking effect to take hold.
Does finasteride affect PSA tests?
Yes — finasteride reduces PSA levels by approximately 50%. Doctors must double the PSA reading when interpreting results in men taking finasteride, to avoid underestimating the risk of prostate cancer. Always inform your doctor you are taking finasteride before a PSA test.
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider with any questions you may have regarding a medical condition or medication. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for the most current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: