Antidepressant switching planner
Pick the FROM drug and the TO drug. The tool returns the switching method (direct switch, cross-taper, or wash-and-switch) based on class and half-life, applies MAOI washout rules when either drug is an MAOI, and prints a day-by-day plan. Every schedule is a reference framework. It doesn't personalize to any patient and it doesn't replace an FDA label review.
Switching plan
Choose a FROM drug, a TO drug, and a start date.
Reference data current as of June 8, 2026. Sources: Maudsley Prescribing Guidelines in Psychiatry, 14th edition; APA Practice Guideline for the Treatment of Patients with Major Depressive Disorder; NICE NG222; FDA prescribing information for MAOIs (14-day washout on either side; 5 weeks after fluoxetine before starting an MAOI).
How to read this
The tool picks a method based on drug class and half-life. Direct switch is the fastest but not always safe. Cross-taper is the default when neither drug is an MAOI. Wash-and-switch is required whenever an MAOI is involved: 14 days between an MAOI and any serotonergic drug, and 5 weeks after fluoxetine before starting an MAOI because norfluoxetine hangs around. Serotonin syndrome is the reason those washouts exist.
Every switch is a conversation with the prescriber. If discontinuation symptoms show up during the taper of the FROM drug, standard practice is to slow the taper rather than push through.
About this tool
Antidepressant switching is one of the most common decisions in outpatient psychiatric practice. It is also one of the least standardized. Every clinician has a preferred approach, and the published literature is thinner than it should be. This tool codifies the switching methods that are widely accepted: direct switch for compatible drugs, cross-taper for most within-class and cross-class switches, and washout for MAOI-involving switches.
The tool implements four decision branches. First, if either drug is an MAOI, the FDA-mandated washout applies: 14 days for standard drugs, 5 weeks if the FROM drug is fluoxetine. Second, SSRI to SSRI or SNRI to SNRI switches between drugs with moderate to long half-lives use a direct switch. Third, any switch involving a short-acting FROM drug (paroxetine, venlafaxine, duloxetine) uses a cross-taper to avoid discontinuation symptoms. Fourth, the default case is a cross-taper with 50/50 overlap for 14 days, which fits most cross-class switches (SSRI to bupropion, SNRI to mirtazapine, TCA to SSRI).
Coverage includes SSRIs (sertraline, escitalopram, citalopram, fluoxetine, paroxetine, fluvoxamine), SNRIs (venlafaxine, duloxetine, desvenlafaxine, levomilnacipran), atypical antidepressants (bupropion, mirtazapine, vortioxetine, vilazodone, trazodone, nefazodone), tricyclics, and MAOIs (phenelzine, tranylcypromine, isocarboxazid, selegiline).
Serotonin syndrome monitoring is worth being explicit about. Any switch that overlaps two serotonergic drugs raises the theoretical risk. In practice, symptoms during a well-managed cross-taper are usually mild (some tremor, mild agitation, transient GI upset) and resolve within days. Severe serotonin syndrome is uncommon but potentially fatal, and it is worth checking pulse, temperature, and neurologic status at every visit during a cross-taper. See the switching antidepressants guide for the full clinical write-up including serotonin syndrome grading and management.
Common questions
- What is a cross-taper switch?
A cross-taper is a switch where the FROM drug is gradually decreased at the same time the TO drug is gradually increased. There is overlap rather than a gap. The two drugs are on board together for a period, usually 1 to 3 weeks. Cross-tapering reduces both discontinuation symptoms from the FROM drug and the wait time for the TO drug to reach effective levels. It is the standard method for most antidepressant switches within and across classes.
- When is a direct switch appropriate?
Direct switching (stop FROM, start TO the next day at a therapeutic dose) is reasonable when both drugs are in the same class with similar receptor profiles and half-lives, especially SSRI to SSRI when neither is short-acting. Direct switches from sertraline to escitalopram, or citalopram to sertraline, work in most patients. Direct switches involving paroxetine, venlafaxine, or duloxetine on the FROM side are usually inadvisable because of discontinuation symptoms.
- What is the MAOI washout period?
Standard MAOI washout after most serotonergic antidepressants is 14 days. After fluoxetine, the washout is 5 weeks because of fluoxetine's long-half-life active metabolite norfluoxetine. The purpose is to avoid serotonin syndrome or hypertensive crisis from combining an MAOI with residual serotonergic drug. This tool applies both rules automatically based on the drugs entered.
- How is serotonin syndrome monitored during a cross-taper?
Serotonin syndrome presents with the triad of mental status changes (agitation, delirium), autonomic instability (tachycardia, hyperthermia, diaphoresis, hypertension), and neuromuscular findings (clonus, hyperreflexia, tremor, rigidity). Mild cases are common during cross-tapers; severe cases are rare but potentially fatal. Practical clinical vigilance during any cross-taper: check pulse and temperature at each visit, ask about tremor, sweating, agitation, or GI symptoms, and stop both drugs if the picture is emerging. Overlap doses of two serotonergic drugs should be the lowest effective doses.
- Should the switch be based on symptom persistence or side effect intolerance?
Both are legitimate switch reasons. Symptom persistence after adequate trial (typically 4 to 8 weeks at optimized dose) often warrants a switch to a different mechanism (SSRI to SNRI, or to an atypical like bupropion, mirtazapine, or vortioxetine). Side effect intolerance often warrants a switch within the same class or to a drug with a different side effect profile (SSRI to bupropion for sexual side effects, for example). The tool covers the mechanics; the clinical rationale belongs with the prescriber.
- What if a patient is already partially responding to the FROM drug?
Partial response often argues for augmentation (adding a second agent like bupropion, mirtazapine, lithium, or aripiprazole) rather than switching, because switching risks losing whatever benefit is present. The STAR*D data supports both switching and augmentation as reasonable next steps after partial response. Whether to switch or augment is a clinical judgment call. This tool covers the switch when that decision is made.