Tizanidine and Famotidine Interaction
Drug interaction information between Tizanidine and Famotidine.
Tizanidine and Famotidine have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Tizanidine and Famotidine. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.
How They Interact
Famotidine can slow down the body's ability to clear tizanidine, which may lead to dangerously high levels of the drug in your blood.
What To Do
Avoid taking these two drugs together if possible to prevent side effects like very low blood pressure or extreme drowsiness.
FDA Label Information
( 7.1 ) • Tizanidine (CYP1A2) Substrate: Potential for substantial increases in blood concentrations of tizanidine resulting in hypotension, bradycardia or excessive drowsiness; avoid concomitant use, if possible. 7.2 Tizanidine (CYP1A2 Substrate) Although not studied clinically, famotidine is considered a weak CYP1A2 inhibitor and may lead to substantial increases in blood concentrations of tizanidine, a CYP1A2 substrate. Refer to the full prescribing information for tizanidine.
Tizanidine Also Interacts With
- Ciprofloxacin major
- Fluvoxamine major
- Acyclovir minor
- Verapamil minor
- Amiodarone minor
Famotidine Also Interacts With
- Theophylline major
- Ketoconazole minor
- Ledipasvir/Sofosbuvir minor
- Itraconazole minor
- Aripiprazole minor
Frequently Asked Questions
Can I take Tizanidine and Famotidine together?
This is a moderate interaction. Avoid taking these two drugs together if possible to prevent side effects like very low blood pressure or extreme drowsiness.
How serious is the interaction between Tizanidine and Famotidine?
This interaction is classified as "moderate" severity by the FDA. Moderate interactions may worsen your condition or change how your medications work.
Why do Tizanidine and Famotidine interact?
Famotidine can slow down the body's ability to clear tizanidine, which may lead to dangerously high levels of the drug in your blood.
Understanding the Tizanidine and Famotidine Interaction
FDA-approved prescribing information for these two drugs flags their combination as a moderate-severity interaction. Tizanidine belongs to the Central Alpha-2 Agonist (Muscle Relaxant) class and Famotidine belongs to the H2 Receptor Antagonist class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Famotidine can slow down the body's ability to clear tizanidine, which may lead to dangerously high levels of the drug in your blood. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.
Context around a specific patient determines real-world impact. Tizanidine has 17 total documented interactions on file in this dataset, and Famotidine has 11. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: Avoid taking these two drugs together if possible to prevent side effects like very low blood pressure or extreme drowsiness. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.
An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Tizanidine or Famotidine based on a web page, speak with your prescriber or pharmacist before making any change.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.
Read our methodology - how this data is sourced, computed, and verified.