The honest answer is that the FDA label does not say dutasteride’s side effects always resolve, and it does not put a figure on how often they do not. The current Avodart label footnotes its adverse-reaction table with this: the sexual adverse reactions associated with dutasteride “may persist after treatment discontinuation. The role of dutasteride in this persistence is unknown.” What the label does quantify is the trend during treatment: reported rates of impotence, decreased libido and ejaculation disorders were highest in the first 6 months and lower in every later 6-month interval. Dutasteride is FDA-approved in the United States for bph/">benign prostatic hyperplasia only; use for hair loss is off-label.
What the Clinical Trials Show
In the pivotal Phase III trials for BPH, sexual side effects were most commonly reported during the first 6 months and were reported less often in each later interval, even with continued dutasteride use. Impotence, for example, fell from 4.7% at months 0-6 to 0.8% at months 19-24, against 1.7% and 0.9% on placebo. The trials did not measure time to resolution after stopping, so no recovery timeline can be quoted from the label. What the label does state is that, because of the long elimination half-life, serum dutasteride concentrations remain detectable (greater than 0.1 ng/mL) for up to 4 to 6 months after discontinuation.
What the FDA Label Actually Says
The current Avodart prescribing information footnotes the sexual adverse reactions in its clinical-trials table as follows: “These sexual adverse reactions are associated with dutasteride treatment (including monotherapy and combination with tamsulosin). These adverse reactions may persist after treatment discontinuation. The role of dutasteride in this persistence is unknown.” The Propecia (finasteride) label carries a parallel entry, listing “sexual dysfunction that continued after discontinuation of treatment” among its post-approval adverse reactions since its April 2012 revision. Neither label states how often this happens, and neither states that the drug caused it.
Factors That May Affect Recovery
- Duration of use: Across the three pivotal placebo-controlled BPH trials, each 4 years long, the label reports no evidence of increased sexual adverse reactions or breast disorders with increased duration of treatment
- Half-life: Dutasteride’s terminal elimination half-life is approximately 5 weeks at steady state, and serum concentrations remain detectable for up to 4 to 6 months after the last dose
- Age: In a single-dose study in 36 healthy men, half-life increased with age, from roughly 170 hours in men aged 20 to 49 to roughly 300 hours in men older than 70. The label reports no overall difference in safety or efficacy between older and younger subjects
- What is not established: No label or trial data assigns a recovery time, identifies who is at risk of persistent symptoms, or establishes a cause. Anything beyond the above is currently hypothesis
The Bottom Line
Reported rates of sexual side effects fell steadily through the trials, and most people who stop a drug stop having its effects. But the label explicitly leaves open the possibility that these reactions persist, and it does not quantify how often. That uncertainty is worth discussing with your prescriber before starting treatment. Any symptoms that persist after discontinuation should be reported to your doctor and to the FDA MedWatch program.
All side effects · Post-finasteride syndrome · Long-term safety
Sources
- FDA. Avodart (dutasteride) prescribing information, NDA 021319 (revision s023/s025), Adverse Reactions and Clinical Pharmacology. accessdata.fda.gov
- FDA. Avodart (dutasteride) prescribing information, current label (revision s032), Adverse Reactions Table 1 footnote. accessdata.fda.gov
- FDA. Propecia (finasteride) prescribing information, revised 04/2012, Postmarketing Experience. accessdata.fda.gov