Cimetidine and Tizanidine interaction
Cimetidine and Tizanidine: the Tizanidine prescribing label 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 Tizanidine (Zanaflex) label · effective 2026-01-02
Zanaflex is contraindicated in patients taking strong CYP1A2 inhibitors [see Drug Interactions ( 7.1 )] . with a history of hypersensitivity to tizanidine or the ingredients in Zanaflex.
Symptoms have included anaphylaxis and angioedema [see Warnings and Precautions ( 5.5 )] Concomitant use with strong CYP1A2 inhibitors ( 4 , 7.1 )
Therefore, concomitant use of Zanaflex with strong CYP1A2 inhibitors is contraindicated [see Contraindications ( 4 ) and Drug Interactions ( 7.1 )] .
Moderate or weak CYP1A2 inhibitors: avoid concomitant use; may cause hypotension, bradycardia, or excessive drowsiness; if concomitant use is necessary and adverse reactions occur, reduce Zanaflex dosage or discontinue.
Clinically significant hypotension (decreases in both systolic and diastolic pressure) has been reported with concomitant administration of tizanidine and strong CYP1A2 inhibitors [see Clinical Pharmacology ( 12.3 )] .
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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.