No SNRI Prevents Hot Flashes—They Are Used to TREAT Them
Your question appears to be based on a misunderstanding: SNRIs do not cause hot flashes; they are actually prescribed to reduce them. Both venlafaxine and desvenlafaxine are effective treatments for hot flashes in menopausal women, including breast cancer survivors 1.
Understanding SNRIs and Hot Flashes
SNRIs Reduce Hot Flashes
All studied SNRIs have demonstrated efficacy in reducing hot flash frequency and severity:
- Venlafaxine: Reduces hot flash scores by 37-61% depending on dose (37.5-150 mg/day), with 75 mg being the optimal dose 1
- Desvenlafaxine: Reduces hot flashes by 64% at 100 mg dose compared to 51% with placebo, with rapid onset of efficacy 1
- Duloxetine: Effective for hot flashes with similar efficacy to other SNRIs 2
Common Side Effects of SNRIs (Not Hot Flashes)
The actual side effects you should expect include 1:
- Dry mouth
- Decreased appetite
- Nausea and constipation
- Sleep disturbance
- Sexual dysfunction (though interestingly, libido increased in some breast cancer patients on venlafaxine)
Clinical Considerations
If You're Experiencing Hot Flashes ON an SNRI
If you're taking an SNRI and still experiencing hot flashes, this likely means:
- The dose may be inadequate: Venlafaxine shows dose-dependent efficacy, with 75 mg being optimal 1
- Individual variability: Some women experience marked variability in response, with 27% potentially having worse symptoms despite treatment 1
- The underlying cause persists: SNRIs treat symptoms but don't address hormonal causes
Alternative Considerations
If an SNRI isn't working for hot flashes, consider 3, 4:
- Switching to a different SNRI (e.g., from venlafaxine to desvenlafaxine)
- Trying an SSRI (paroxetine, citalopram, escitalopram)—though avoid paroxetine if taking tamoxifen 1, 5
- Gabapentin or pregabalin (particularly effective for nighttime hot flashes)
- Hormone therapy if not contraindicated (most effective option)
Important Caveat
Some women do experience exacerbation of vasomotor symptoms on antidepressants—this occurs in a minority but is documented 1. If you're in this group, discontinue the SNRI gradually and try an alternative class like gabapentin.