Dutasteride Side Effects
Dutasteride side effects are usually mild and transient. Drug related adverse effects of dutasteride certainly appear to be less than those associated with finasteride. The most common side effects of dutasteride are sexual effects including:
- impotence
- decreased libido
- ejaculation disorders
- gynecomastia (breast tenderness)
Dutasteride side effects discovered in a clinical study are summarized in the table below. Approxiamtely 6% of each group (dutasteride and placebo) withdrew from the study due to adverse events, with the investigator attributing less than half of these withdrawals to drug related adverse effects.
Summary of Dutasteride Side Effects
| Side Effect | Dutasteride (n=2158) | Placebo (n=2166) |
|---|---|---|
| Impotence | 117(5%) | 59 (3%) |
| Decreased Libido | 74 (3%) | 40 (2%) |
| Gynecomastia | 29(1%) | 10 (<1%) |
| Ejaculation Disorder | 40 (2%) | 14 (<1%) |
Side Effects of Long-Term Treatment with Dutasteride
The incidence of sexual adverse events considered to be drug-related decreased with duration of treatment. After the 6 months of treatment impotence, decreased libido, ejaculation disorders and gynecomastia were all <1% for both the dutasteride and placebo groups.
The incidence of drug-related events was lower during the second year of treatment compared with the first year of treatment. The only exception was gynecomastia which increased from 1% in the first year to 2% in the second year.
The table below shows the results of a study performed by Roehrborn et al (Efficacy and Safety of a Dual Inhibitor of 5-Alpha-Reductase Types 1 and 2 (Dutasteride) In Men With Benign Prostatic Hyperplasia", Roehrborn et al, Urology 60:434-441, 2002). The results show a significant decrease in side effect profiles as the treatment duration increases.
Summary of Long-Term Dutasteride Side Effects
| Side Effect | First Year | Second Year | Total Study | |||
|---|---|---|---|---|---|---|
| Dutasteride | Placebo | Dutasteride | Placebo | Dutasteride | Placebo | |
| Impotence | 130 (6.0%) | 65 (3.0%) | 29 (1.7%) | 21 (1.2%) | 158 (7.3%) | 86 (4.0%) |
| Decreased Libido | 80 (3.7%) | 41 (1.9%) | 11 (0.6%) | 6 (0.3%) | 91 (4.2%) | 46 (2.1%) |
| Gynecomastia | 28 (1.3%) | 11 (0.5%) | 23 (1.3%) | 5 (0.3%) | 50 (2.3%) | 16 (0.7%) |
| Ejaculation Disorder | 40 (1.8%) | 15 (0.7%) | 9 (0.5%) | 2 (0.1%) | 48 (2.2%) | 17 (0.8%) |
Dutasteride & Shedding
Dutasteride may cause an initial period of shedding approximately six to eight weeks into treatment. This is a normal response to treatment with dutasteride. For more information, see our page about dutasteride shedding.