How to taper fluoxetine (SSRI) from 20 mg?

How to Decrease Fluoxetine from 20 mg

Fluoxetine does not require gradual tapering when discontinuing from 20 mg daily due to its exceptionally long elimination half-life of 4-6 days (and its active metabolite norfluoxetine has a half-life of 4-16 days), which provides a built-in buffer against withdrawal symptoms—you can simply stop the medication abruptly. 1, 2, 3

Why Fluoxetine is Unique Among Antidepressants

• Fluoxetine is the only SSRI that does not require tapering because its long half-life creates a natural, gradual decline in drug levels over weeks after discontinuation 2, 3
• The FDA label explicitly states that "active drug substance will persist in the body for weeks" after dosing is stopped, depending on individual patient characteristics and length of previous therapy 1
• After stopping fluoxetine 20 mg daily, plasma concentrations decline slowly and naturally over 4-6 weeks, mimicking what a taper would accomplish with other SSRIs 1

If You Still Prefer a Gradual Approach

While not medically necessary for fluoxetine specifically, if you want to reduce the dose before stopping:

• Reduce to 10 mg daily for 1-2 weeks, then discontinue 1
• This approach may provide psychological reassurance to patients anxious about stopping medication, though it offers no pharmacological advantage given fluoxetine's kinetics 1

Monitoring After Discontinuation

• Monitor for withdrawal symptoms weekly for the first month after stopping, though these are rare with fluoxetine compared to other SSRIs 2
• Common SSRI withdrawal symptoms (if they occur) include dizziness, nausea, fatigue, sensory disturbances, anxiety, and irritability 2
• Distinguish withdrawal symptoms from depression relapse: withdrawal symptoms typically emerge within 1-2 weeks of stopping and are self-limited, while relapse develops more gradually over weeks to months 2

Critical Pitfalls to Avoid

• Do not confuse fluoxetine with other SSRIs like paroxetine, sertraline, or fluvoxamine, which DO require slow tapers over weeks to months 2, 4
• Do not apply hyperbolic tapering principles (used for short half-life SSRIs) to fluoxetine—this is unnecessary and prolongs treatment without benefit 4
• Be aware that fluoxetine inhibits CYP2D6, so drug interactions may persist for weeks after discontinuation due to the long half-life 1

Special Populations

• Patients with liver disease: Fluoxetine's half-life extends to 7.6 days (vs 2-3 days in healthy patients), so even more gradual natural decline occurs after stopping 1
• Elderly patients: No special tapering considerations needed; single-dose studies showed no significant pharmacokinetic differences, though the long half-life provides extra safety 1
• Pediatric patients: The same principles apply—no taper required from 10-20 mg daily doses 1

When Symptoms Occur Despite Fluoxetine's Long Half-Life

• If withdrawal symptoms emerge (uncommon but possible), they are typically mild and self-limiting 2, 3
• Reassure the patient that symptoms are transient and usually resolve within days to 1-2 weeks 2
• If symptoms are severe, consider restarting fluoxetine 10-20 mg briefly, then stopping again after stabilization 2