Switching from Selective Serotonin Reuptake Inhibitors to Serotonin-Norepinephrine Reuptake Inhibitors
Understanding the Medications
- The American Academy of Child and Adolescent Psychiatry notes that Fluoxetine has a very long half-life of 4-6 days, which provides a natural buffer against discontinuation symptoms 1, 2
- The American Academy of Child and Adolescent Psychiatry states that Desvenlafaxine is a serotonin-norepinephrine reuptake inhibitor with a shorter half-life, making it more prone to causing discontinuation symptoms if stopped abruptly 3
Recommended Switching Protocol
Step 1: Preparation
- The American Family Physician recommends consulting with your prescribing physician before making any changes to your medication regimen 4
Step 2: Cross-Tapering Approach
- The American Academy of Child and Adolescent Psychiatry suggests starting Desvenlafaxine at the initial recommended dose while continuing your current dose of Fluoxetine, then gradually reducing the Fluoxetine dose after 1-2 weeks 1, 3
- The American Family Physician notes that Fluoxetine's long half-life provides a natural, gradual taper effect, making it one of the easiest antidepressants to discontinue 1, 2
Step 3: Reduction Schedule
- The American Family Physician recommends reducing Fluoxetine dose by half for 1-2 weeks, then discontinuing completely for patients on 20mg, and reducing by 10-20mg every 2 weeks until reaching 10mg for those on higher doses 1
Special Considerations
- The American Academy of Child and Adolescent Psychiatry states that Desvenlafaxine may cause different side effects than Fluoxetine, including increased blood pressure and pulse, which should be monitored 3
- The American Family Physician notes that some patients may experience initial side effects when starting Desvenlafaxine, including nausea, dizziness, sweating, and insomnia 3, 4