Sexual side effects are the most commonly reported adverse effects of dutasteride. In the pooled placebo-controlled BPH trials, the FDA label reports that during months 0-6 impotence occurred in 4.7% of men on dutasteride (vs 1.7% on placebo), decreased libido in 3.0% (vs 1.4%), and ejaculation disorders in 1.4% (vs 0.5%). Reported rates were highest in the first 6 months and fell in each later interval. Dutasteride is FDA-approved in the United States for benign prostatic hyperplasia only; use for hair loss is off-label.
Types of Sexual Side Effects
Erectile Dysfunction
Erectile dysfunction, recorded in the FDA label as impotence, is the most commonly reported sexual side effect. In the pooled BPH trials it was reported by 4.7% of men on dutasteride during months 0-6 versus 1.7% on placebo, then by 1.4%, 1.0% and 0.8% in the three following 6-month intervals, against 1.5%, 0.5% and 0.9% on placebo. The label states there was no evidence of increased sexual adverse reactions with increased duration of treatment.
Decreased Libido
Decreased libido (reduced sexual desire) was reported by 3.0% of men on dutasteride versus 1.4% on placebo during months 0-6, falling to 0.7%, 0.3% and 0.3% in the three following 6-month intervals. Dutasteride blocks the conversion of testosterone to DHT, and the label does not state a mechanism for this effect.
Ejaculation Disorders
Ejaculation disorders were reported by 1.4% of men on dutasteride versus 0.5% on placebo during months 0-6. In a separate 52-week study of semen characteristics in healthy volunteers, the label records a mean reduction from baseline in semen volume of 26%.
Do Sexual Side Effects Resolve?
The current FDA prescribing information does not state that these effects always resolve. Its Table 1 footnote reads: “These adverse reactions may persist after treatment discontinuation. The role of dutasteride in this persistence is unknown.” Because of the drug’s long elimination half-life of approximately 5 weeks, serum concentrations remain detectable for up to 4 to 6 months after the last dose. Some patients report persistent sexual dysfunction: see post-finasteride syndrome.
Managing Sexual Side Effects
- Dose reduction: Some prescribers use twice-weekly dosing off-label to reduce systemic exposure. The FDA label recommends 0.5 mg once daily and does not describe any lower-frequency schedule
- Wait: In the BPH trials, reported rates of impotence, decreased libido and ejaculation disorders were highest in the first 6 months and lower in every later interval
- Ask about topical: Topical dutasteride is a compounded, off-label preparation. There is no FDA-approved topical dutasteride product and no approved-label data on it
- Discontinue: Discuss stopping with your prescriber. The label notes these reactions may persist after discontinuation and that dutasteride’s role in that persistence is unknown
- Consult your doctor: Discuss alternative treatments or adjunctive therapies
All side effects · Are they permanent? · Long-term safety
Sources
- FDA. Avodart (dutasteride) prescribing information, NDA 021319 (revision s023/s025). accessdata.fda.gov
- FDA. Avodart (dutasteride) prescribing information, current label (revision s032), Adverse Reactions Table 1. accessdata.fda.gov