Propecia (Finasteride)

What is Propecia?

Propecia is an oral prescription medicine containing finasteride 1 mg. Its Spanish authorisation concerns men aged 18–41 with early androgenetic alopecia. It can stabilise hair loss; efficacy is not established for bitemporal recession or end-stage hair loss.

A diagnosis matters because not all hair loss has the same cause. This article does not guarantee regrowth or establish suitability for an individual.

How does it work?

Finasteride inhibits type II 5-alpha reductase, reducing conversion of testosterone to dihydrotestosterone (DHT). This acts on a process responsible for miniaturisation of susceptible scalp follicles. The mechanism differs from topical minoxidil; it does not justify ranking either as universally better.

Who must not use it?

Propecia is contraindicated in women and in anyone allergic to finasteride or an excipient. It must not be used in children; safety and efficacy below 18 years are not established.

Women who are pregnant or could become pregnant must not handle crushed or broken tablets because absorption may harm the external genital development of a male foetus. The coating prevents contact during normal handling of intact tablets.

Liver impairment is unstudied and requires assessment; it is not listed as an absolute contraindication. No renal dose adjustment is needed. Tell the clinician about liver disease, fertility plans, prostate or urinary problems, sexual dysfunction and any history of depression or other mood disorders.

Dosage and response

Increasing the dose has not shown greater efficacy. Benefit and duration should be reviewed continuously. Stabilisation generally takes 3–6 months. If treatment stops, benefits begin to disappear by 6 months and the pretreatment state returns within 9–12 months.

Do not continue despite urgent safety symptoms merely to maintain hair growth.

Side effects and actions

Uncommon effects

Decreased libido, erectile dysfunction, ejaculatory disorders (including reduced semen volume) and depression are classified as uncommon (at least 1 in 1,000 but fewer than 1 in 100) in the Spanish label. The sexual-effect categories use differences from placebo; they are not a claim that the combined trial event rate was below 1%.

Reports with unknown frequency

These include anxiety, suicidal ideation, palpitations, increased liver enzymes, breast tenderness/enlargement, testicular pain, blood in semen, infertility and hypersensitivity. Persistent sexual dysfunction after stopping and male breast cancer have also been reported. Do not dismiss persistence as merely speculative or assign a frequency not established by the label.

Mood changes: stop finasteride and seek medical advice if depressed mood, depression or other psychiatric symptoms appear. Thoughts of self-harm require urgent help. The patient information card reinforces these warnings.

Sexual dysfunction: contact the clinician; stopping treatment should be considered. Sexual problems may contribute to mood changes, including suicidal thoughts.

Breast changes: promptly report a lump, pain, enlargement or nipple discharge. Severe allergy: stop and obtain emergency care for swelling of lips, tongue, face or throat or breathing difficulty.

Fertility and semen-quality problems have been reported; improvement after stopping has also been reported. Discuss fertility plans rather than assuming no risk or certain reversibility.

PSA blood tests

Tell any clinician ordering a prostate-specific antigen (PSA) test that you take finasteride. In studies of Propecia in men aged 18–41, mean PSA fell from 0.7 ng/mL to 0.5 ng/mL after 12 months. This is not a universal 50% reduction.

The label separately says that doubling the measured PSA should be considered when interpreting results. That is a clinical interpretation rule, not a way to calculate an individual’s “true” value or diagnose cancer yourself. Propecia 1 mg is not the separate higher-dose treatment for benign prostatic hyperplasia.

Other treatments and interactions

Topical minoxidil has different mechanisms, formulations and population-specific instructions. Spain’s Regaine 50 mg/g foam is for men; women’s products have their own labels. Do not transfer one minoxidil dosing schedule to all products. The hair-growth benefit of either treatment depends on continued appropriate use, but their stopping timelines differ.

The prescriber should review any proposed combination. This article makes no blanket combination-safety or additive-benefit claim.

Disclose all medicines. CYP3A4 inhibitors and inducers can affect finasteride levels; the label expects a low risk of clinically significant interactions, which is not the same as an individual clearance. Propecia contains lactose and must not be used in the specified hereditary galactose/lactase/glucose-galactose disorders.

Accessing an assessment

Prescrivia is a technology intermediary; it does not prescribe medicines, employ doctors or sell medicines.

1. Provide hair-loss history, medical history, medicines and previous treatments.
2. An independent doctor assesses suitability and may issue a prescription.
3. A licensed pharmacy assesses dispensing and delivery under applicable rules and availability.

No prescription, supply or treatment outcome is guaranteed.

In Spain, distance sale of prescription medicines is prohibited under Article 3.5 of Royal Legislative Decree 1/2015. An online assessment does not remove this restriction. Dispensing and access depend on the exact product and applicable national rules.

Sources

• AEMPS CIMA: Propecia 1 mg, sections 4.1–4.8 and 5.1.
• AEMPS: finasteride mood and sexual-function safety advice, patient/professional recommendations, read alongside the updated product information.
• AEMPS CIMA: Regaine men’s foam, formulation and indication.

Read the full leaflet and patient card. This selected information does not replace individual medical advice.