Finasteride: NHS prescribing information and patient guide

Finasteride is a 5-alpha reductase inhibitor that reduces the production of dihydrotestosterone (DHT), a hormone derived from testosterone.

1. Male pattern hair loss (androgenetic alopecia) at 1 mg daily:

• Finasteride 1 mg slows hair loss and can promote regrowth in men with male pattern baldness
• It is most effective for hair loss at the crown and mid-scalp
• Results take at least 3 to 6 months to become visible, and continued use is needed to maintain benefits
• If treatment is stopped, hair loss resumes within 6 to 12 months

2. Benign prostatic hyperplasia (BPH) at 5 mg daily:

• Finasteride 5 mg shrinks an enlarged prostate gland, relieving urinary symptoms
• It reduces the risk of acute urinary retention and the need for prostate surgery
• Benefits are typically seen after 6 to 12 months of continuous use
• It is often prescribed alongside an alpha-blocker such as tamsulosin for more immediate symptom relief

How does finasteride work?

The enzyme 5-alpha reductase converts testosterone to DHT. In the scalp, excess DHT causes hair follicles to shrink, leading to hair thinning and loss. In the prostate, DHT drives glandular growth.

By blocking this enzyme, finasteride reduces DHT levels by approximately 65 to 70 per cent, addressing both conditions at their hormonal root.

The NHS availability of finasteride differs depending on the indication.

For benign prostatic hyperplasia (5 mg):

• Finasteride 5 mg is available on NHS prescription for men with symptomatic BPH
• It is listed in the BNF and widely prescribed by GPs and urologists
• Generic finasteride 5 mg is very affordable, costing only a few pence per tablet
• Standard NHS prescription charges apply, though many patients with chronic conditions may be exempt

For hair loss (1 mg):

• Finasteride 1 mg for hair loss is not routinely available on the NHS
• Hair loss is generally considered a cosmetic concern by the NHS, and funding is not provided
• You will need a private prescription, which can be obtained from your GP (who may charge a private consultation fee) or from an online prescribing service
• The cost of finasteride 1 mg is relatively low, typically around 10 to 30 pounds for a month's supply from online pharmacies

Important notes:

• Some men ask their GP to prescribe finasteride 5 mg tablets on the NHS and then cut them into quarters to treat hair loss. While some doctors may discuss this off-label approach, it is not officially recommended, and the dose delivered may be inconsistent
• The Medicines and Healthcare products Regulatory Agency (MHRA) has approved finasteride 1 mg specifically for hair loss under the brand name Propecia and various generic alternatives

Before prescribing finasteride, your doctor should consider several factors to ensure the medication is appropriate for you.

Before starting finasteride:

• A discussion about potential side effects, including sexual side effects and the rare risk of mood changes
• Assessment of your mental health history, particularly any history of depression or anxiety
• For BPH: a digital rectal examination and PSA blood test may be performed to rule out prostate cancer
• Confirmation that you are male (finasteride is not licensed for women)

During treatment:

• For hair loss (1 mg): routine blood tests are not required, but your doctor should check in about side effects at follow-up
• For BPH (5 mg): regular PSA monitoring is recommended, as finasteride reduces PSA levels by approximately 50 per cent. This must be factored into prostate cancer screening
• Report any mood changes, sexual dysfunction, or breast changes promptly

PSA and prostate cancer screening:

• Finasteride halves PSA levels, so any PSA result while on treatment should be doubled for accurate interpretation
• An unexpected rise in PSA while on finasteride should be investigated, even if the absolute value appears normal
• The MHRA advises that prescribers and patients are aware of this effect

Duration of treatment:

• For hair loss: treatment is ongoing. Benefits are lost within 6 to 12 months of stopping
• For BPH: long-term use is typical, with periodic review of symptoms and prostate size

Fertility considerations are important for men of reproductive age who are considering finasteride treatment.

Effects on sperm:

• Finasteride can reduce sperm count, semen volume, and sperm motility in some men
• These effects are generally reversible after stopping the medication
• The BNF notes that these changes are usually not clinically significant for most men

If you are trying to conceive:

• Discuss the use of finasteride with your doctor if you are planning to start a family
• Some fertility specialists recommend stopping finasteride at least three months before attempting conception, to allow sperm parameters to normalise
• There is no evidence that finasteride causes birth defects when taken by the father, but the precautionary advice is to stop if possible

Handling precautions:

• Women who are or may become pregnant must not handle crushed or broken finasteride tablets
• Finasteride can be absorbed through the skin and may harm a developing male foetus by affecting genital development
• Intact tablets with their coating intact are safe to handle

Blood donation:

• Men taking finasteride should not donate blood during treatment and for at least one month after stopping
• This is to prevent the medication from being given to a pregnant woman through a blood transfusion

If finasteride is not suitable for you, or if you prefer to explore other options, there are alternatives available.

For hair loss:

• Minoxidil (Regaine): a topical treatment available over the counter without a prescription. It works differently from finasteride and can be used alone or in combination
• Hair transplant surgery: not available on the NHS for cosmetic hair loss, but may be considered privately
• Camouflage techniques: scalp micropigmentation and hair fibres are non-medical options
• Counselling and support: if hair loss is significantly affecting your mental health, your GP can refer you for psychological support on the NHS

For BPH:

• Alpha-blockers (tamsulosin, alfuzosin, doxazosin): relax the muscles around the prostate and bladder neck, providing quicker symptom relief than finasteride
• Dutasteride: another 5-alpha reductase inhibitor that blocks both type 1 and type 2 enzymes. Available on NHS prescription for BPH
• Combination therapy: finasteride or dutasteride combined with an alpha-blocker for men with larger prostates
• Surgical options: transurethral resection of the prostate (TURP), laser prostatectomy, and other procedures are available on the NHS for men whose symptoms are not adequately controlled by medication

Your GP or specialist can discuss which option is most appropriate based on your symptoms, preferences, and medical history.