Cyclobenzaprine and Ondansetron interaction
Cyclobenzaprine and Ondansetron: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Cyclobenzaprine (TONMYA) label · effective 2026-08-14
If serotonin syndrome symptoms occur with the use of other serotonergic drugs, immediately discontinue TONMYA.
Other serotonergic Drugs: Serotonin syndrome has been reported ( 5.2 , 7 )
If concomitant treatment with TONMYA and other serotonergic drugs is clinically warranted, careful observation is advised, particularly during treatment initiation or dosage increases.
If concomitant treatment with TONMYA and other serotonergic drugs (besides MAO inhibitors) is clinically warranted, careful observation is advised, particularly during dosage increases.
From the Ondansetron label · effective 2026-04-16
Patients should be monitored for the emergence of serotonin syndrome, especially with concomitant use of Ondansetron Injection and other serotonergic drugs.
Patients should be informed of the increased risk of serotonin syndrome, especially if Ondansetron Injection is used concomitantly with other serotonergic drugs [see Drug Interactions (7.5 ), Overdosage (10) ] .
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.