How long do Effexor (venlafaxine) side effects last?

Duration of Effexor (Venlafaxine) Side Effects

Most side effects of Effexor emerge within the first few weeks of treatment, with the majority resolving within 1 to 3 weeks, though some may persist throughout treatment. 1

Timeline of Side Effect Resolution

Early Side Effects (First 1-3 Weeks)

• Nausea, the most common side effect, typically resolves rapidly within the first 1 to 3 weeks of therapy 2
• Other common early side effects include dizziness, somnolence, insomnia, dry mouth, sweating, nervousness, and constipation 2
• These gastrointestinal and nervous system effects generally emerge within the first few weeks but tend to diminish as treatment continues 1

Persistent Side Effects

• Some adverse effects may continue throughout treatment, including:
  • Sexual dysfunction (abnormal ejaculation, erectile problems) 2, 3
  • Sweating 2
  • Blood pressure elevations (dose-dependent, occurring in 3-5% at ≤200 mg/day, 7% at 201-300 mg/day, and 13% at >300 mg/day) 2

Discontinuation Syndrome

• A withdrawal syndrome has been described with venlafaxine, requiring tapering over 10 to 14 days when discontinuing to limit withdrawal symptoms 1
• This discontinuation syndrome can occur following missed doses or acute discontinuation 1
• Slow discontinuation taper is warranted to minimize withdrawal effects 1

Clinical Monitoring Recommendations

• Most adverse effects manifest within the first few weeks of treatment 1
• Close monitoring is particularly important during:
  • The first months of treatment 1
  • Following dosage adjustments 1
  • Titration period (typically 2 to 4 weeks to reach efficacious dosage of 150-225 mg/day) 1

Important Caveats

• Behavioral activation/agitation may occur early in treatment or with dose increases, supporting the need for slow up-titration and close monitoring 1
• Cardiac conduction abnormalities and blood pressure increases can occur, requiring caution in patients with cardiac disease 1
• The side effect profile is generally similar to SSRIs rather than tricyclic antidepressants, with better tolerability 4, 3