Can Effexor (venlafaxine) cause hot flashes?

Can Effexor (Venlafaxine) Cause Hot Flashes?

No, Effexor (venlafaxine) does not cause hot flashes; it is actually recommended as a first-line treatment for hot flashes with an optimal dose of 75 mg/day, which reduces hot flash scores by 61% compared to placebo. 1

Evidence for Venlafaxine as a Hot Flash Treatment

Venlafaxine is well-established as an effective treatment for hot flashes rather than a cause:

• The American Society of Clinical Oncology recommends venlafaxine as a first-line treatment for hot flashes 1
• At 75 mg/day, venlafaxine reduces hot flash scores by 61% compared to placebo 1, 2
• Lower doses (37.5 mg/day) show more modest reductions of 37% in hot flash scores 2, 3
• Higher doses (150 mg/day) don't provide additional benefit beyond 75 mg/day but may increase side effects 1, 2

Side Effects of Venlafaxine

While venlafaxine treats hot flashes rather than causing them, it does have common side effects that should be monitored:

• Common side effects include:

  • Nausea (37% vs 11% for placebo) 4
  • Dry mouth (22% vs 11% for placebo) 4
  • Dizziness (19% vs 7% for placebo) 4
  • Somnolence/drowsiness (23% vs 9% for placebo) 4
  • Sweating (increased incidence with higher doses) 4
  • Sexual dysfunction (abnormal ejaculation/orgasm in 12% of men vs 2% for placebo) 4

• Discontinuation rates due to side effects:

  • 10-20% of patients discontinue venlafaxine due to side effects 5
  • In clinical trials, 19% (537/2897) of venlafaxine patients discontinued treatment due to adverse events 4

Discontinuation Symptoms

When stopping venlafaxine, gradual tapering is essential to prevent withdrawal symptoms, which can include:

• Dizziness, sensory disturbances (including shock-like electrical sensations)
• Anxiety, irritability, agitation
• Nausea, headache, fatigue
• Insomnia, nightmares, emotional lability 4

Clinical Application

For patients experiencing hot flashes:

1. Starting dose: Begin with 37.5 mg/day for one week 1, 2
2. Target dose: Increase to 75 mg/day for optimal effect (61% reduction in hot flashes) 1, 2
3. Duration: Assess response after 4 weeks of treatment 1
4. Discontinuation: Taper gradually to avoid withdrawal symptoms 1, 4

Special Considerations

• Venlafaxine is particularly useful for hot flashes in patients who cannot take hormonal therapy, such as breast cancer survivors 2
• Unlike paroxetine, venlafaxine has minimal interaction with tamoxifen metabolism, making it a preferred choice for breast cancer patients on tamoxifen 1
• At least 50% relief in physiological hot flashes may be needed for patients to demonstrate improvement in other outcomes, including decreased fatigue, improved sleep, and improved quality of life 6

In summary, venlafaxine is a treatment for hot flashes rather than a cause of them, with substantial evidence supporting its efficacy in reducing hot flash frequency and severity.