From the Guidelines
Yes, sexual side effects of Propecia (finasteride) can occur later in treatment, as evidenced by the Prostate Cancer Prevention Trial (PCPT) which showed that the relative risk of sexual side effects, such as erectile dysfunction, decreased libido, and decreased ejaculate volume, increased with long-term treatment duration of 2 years or more 1.
Key Findings
- The PCPT study found that the relative risk of erectile dysfunction was 1.10 (95% CI 1.07 to 1.12) with long-term treatment duration of 2 years or more 1.
- Decreased libido was also more common with long-term treatment, with a relative risk of 1.10 (95% CI 1.07 to 1.12) 1.
- Decreased ejaculate volume was reported in 60.4% of patients with long-term treatment, compared to 47.3% with placebo, with a relative risk of 1.28 (95% CI 1.24 to 1.31) 1.
Mechanism of Action
The sexual side effects of Propecia are thought to be related to its mechanism of action, which involves the inhibition of the enzyme 5-alpha reductase, leading to a decrease in dihydrotestosterone (DHT) levels 1. While reducing DHT helps prevent hair loss, it can also affect sexual function since DHT plays a role in male sexual health.
Management Options
For patients experiencing sexual side effects, options include discontinuing the medication, reducing the dose to 0.5mg daily, or switching to a topical formulation. However, it's essential to note that for some patients, these sexual side effects may persist even after stopping the medication, a condition sometimes called Post-Finasteride Syndrome, though this remains controversial in the medical community.
Clinical Implications
The risk of sexual side effects with long-term finasteride use should be carefully considered and discussed with patients before initiating treatment. Patients should be monitored for sexual side effects, and alternative treatments should be considered if these side effects occur or persist.
From the FDA Drug Label
The relationship between long-term use of finasteride and male breast neoplasia is currently unknown Sexual Function There is no evidence of increased sexual adverse experiences with increased duration of treatment with finasteride tablets. New reports of drug-related sexual adverse experiences decreased with duration of therapy.
- sexual dysfunction that continued after discontinuation of treatment, including erectile dysfunction, decreased libido and ejaculation disorders (e. g. reduced ejaculate volume).
Sexual side effects of Propecia (finasteride) can occur at any time during treatment, including later in treatment. Although the label states that new reports of drug-related sexual adverse experiences decreased with duration of therapy, it also notes that sexual dysfunction can continue after discontinuation of treatment. Therefore, it is possible for sexual side effects to occur or persist later in treatment 2.
- Key points:
- No evidence of increased sexual adverse experiences with increased duration of treatment
- New reports of drug-related sexual adverse experiences decreased with duration of therapy
- Sexual dysfunction can continue after discontinuation of treatment
From the Research
Sexual Side Effects of Propecia (Finasteride)
- The sexual side effects of Propecia (finasteride) can occur later in treatment, and in some cases, may persist despite discontinuation of the medication 3, 4.
- Studies have shown that the types of persistent sexual side effects associated with finasteride include low libido, erectile dysfunction, decreased arousal, and problems with orgasm 3.
- The mean duration of finasteride use was 28 months, and the mean duration of persistent sexual side effects was 40 months from the time of finasteride cessation to the interview date 3.
- Another study found that 96% of subjects with persistent sexual side effects associated with finasteride continued to experience these effects after 9-16 months (mean 14 months) 4.
- The Arizona Sexual Experience Scale (ASEX) scores indicated that 89% of subjects met the definition of sexual dysfunction, and neither the length of finasteride use nor the duration of the sexual side effects correlated to changes in scores of sexual dysfunction 4.
Risk of Persistent Sexual Side Effects
- The risk of persistent sexual side effects associated with finasteride is a concern, and physicians should discuss this potential risk with patients before starting treatment 3, 5, 6.
- A systematic review and meta-analysis found that the use of 5α-reductase inhibitors, including finasteride, carried a 1.57-fold risk of sexual dysfunction (95% confidence interval (95% CI) 1.19-2.08) 6.
- The relative risk was 1.66 (95% CI 1.20-2.30) for finasteride, indicating a significant increase in the risk of sexual dysfunction associated with this medication 6.