Serotonin syndrome risk checker
Add each medication a patient is on. The tool flags combinations that carry serotonin syndrome risk based on published pharmacology. Warnings are reference-side lookups, not personalized recommendations.
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Interaction analysis
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Reference data current as of July 2026. Sources: Boyer EW, Shannon M. The serotonin syndrome. N Engl J Med. 2005; FDA prescribing information; Dunkley et al. QJM 2003 (Hunter criteria).
About this tool
Serotonin syndrome is a life-threatening reaction from too much central serotonergic activity, usually from drug combinations. This tool takes a list of medications and flags combinations known to carry meaningful serotonin syndrome risk based on published pharmacology.
The intensity classifications are: strong (MAOIs, meperidine with MAOI, MDMA with SSRIs), moderate (SSRIs, SNRIs, tramadol, clomipramine, St. John's wort), and weak (trazodone, mirtazapine, triptans, ondansetron, dextromethorphan at usual doses). Any combination involving an MAOI with a moderate or strong serotonergic drug requires the standard 14-day washout, or 5 weeks after fluoxetine.
The tool is a reference lookup. Actual serotonin syndrome risk depends on doses, duration, patient factors, and timing that this tool does not know. Every prescribing decision belongs with the licensed clinician.
Common questions
- How does this tool assess serotonin syndrome risk?
The tool classifies each entered drug as strong, moderate, weak, or contested for serotonergic activity based on published pharmacology. It flags high-risk combinations: any two strong-serotonergic drugs, MAOI plus anything serotonergic, tramadol plus SSRI/SNRI, meperidine plus MAOI. Warnings are reference-side, not personalized recommendations.
- What combinations are most dangerous?
MAOI plus SSRI or SNRI (14-day washout required, 5 weeks after fluoxetine). MAOI plus tramadol, meperidine, dextromethorphan, or St. John's wort. SSRI plus tramadol at higher doses. Multiple serotonergic drugs stacked. See our serotonin syndrome page for full detail on presentation and Hunter criteria.
- Does this replace clinical judgment?
No. It flags pharmacologic combinations. It does not know dose, duration, patient history, or the reason each drug is prescribed. Every prescribing decision belongs with the licensed clinician. See our SSRI plus tramadol page for how to think about specific combinations.