Which is more likely to cause erectile dysfunction, Straterra (atomoxetine) or gabapentin?

Atomoxetine (Strattera) is More Likely to Cause Erectile Dysfunction Than Gabapentin

Based on the FDA drug label evidence, atomoxetine has a significantly higher risk of causing erectile dysfunction compared to gabapentin, with erectile dysfunction occurring in 8% of adult males taking atomoxetine versus placebo (1.9%). 1

Comparison of Sexual Side Effect Profiles

Atomoxetine (Strattera) Sexual Side Effects

• Erectile dysfunction: 8% of adult males (vs 1.9% with placebo) 1
• Ejaculation disorders: 4% of adult males (vs 1.1% with placebo) 1
• Decreased libido: 4.6% of adult males (vs 3.0% with placebo) 1
• Urinary hesitation: 6.9% of adult males (vs 2.4% with placebo) 1

The FDA label explicitly states that "atomoxetine appears to impair sexual function in some patients" and acknowledges that these rates likely underestimate the actual incidence due to underreporting 1.

Gabapentin Sexual Side Effects

• While gabapentin can cause sexual dysfunction, it appears to be less common and typically occurs at higher doses (900mg daily or more) 2
• There is a case report of total sexual dysfunction (including impotence) at a lower dose of 300mg daily, but this appears to be uncommon 2

Time Course and Resolution of Sexual Side Effects

For atomoxetine:

• Sexual side effects typically develop early in treatment:
  • Genitourinary issues within the first 2 weeks
  • Erectile and ejaculation issues during the second and third week of treatment 3
• Median time to resolution ranges from 3-8 weeks after onset 3
• Sexual side effects may persist throughout treatment

For gabapentin:

• Sexual dysfunction appears to be dose-dependent 2
• Limited evidence suggests it may be reversible upon discontinuation or dose reduction

Risk Factors and Special Populations

Atomoxetine

• CYP2D6 poor metabolizers have significantly higher rates of erectile dysfunction (21% vs 9% in extensive metabolizers) 1
• Adult males are at much higher risk than adolescent males or females 3
• Concomitant use of CYP2D6 inhibitors (like paroxetine or fluoxetine) increases the risk 1

Gabapentin

• Higher doses (>900mg daily) appear to increase risk 2
• Individual susceptibility varies significantly

Clinical Management Approach

1. For patients at high risk for erectile dysfunction:

   • Consider gabapentin over atomoxetine if clinically appropriate
   • For patients requiring atomoxetine, use the lowest effective dose

2. For patients already experiencing erectile dysfunction:

   • If on atomoxetine, consider switching to an alternative medication
   • If on gabapentin, consider dose reduction if clinically feasible

3. Monitoring recommendations:

   • Proactively inquire about sexual side effects, as patients may be reluctant to report them spontaneously 1
   • Assess at baseline and regularly during follow-up visits

Conclusion

When considering the risk of erectile dysfunction between these two medications, atomoxetine carries a substantially higher and better-documented risk compared to gabapentin. The FDA label for atomoxetine specifically lists erectile dysfunction as a common adverse effect occurring in 8% of adult males, while gabapentin's association with sexual dysfunction appears less frequent and primarily dose-dependent.