Drug interactions
Phentolamine + Tizanidine
Severity: Moderate
Phentolamine and Tizanidine: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Phentolamine blocks alpha-adrenergic receptors causing vasodilation, while tizanidine lowers sympathetic outflow centrally. Together they can cause additive hypotension and reflex tachycardia.
What this interaction means in plain words
Phentolamine and Tizanidine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Phentolamine belongs to Cardiovascular; Tizanidine belongs to Musculoskeletal.
Why it happens
Additive pharmacodynamic hypotension from central alpha-2 agonism and peripheral alpha-adrenergic blockade.
What to do
Monitor blood pressure and heart rate closely when the two are used together. Reduce the dose of one agent if significant hypotension occurs.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Tizanidine
- Ciprofloxacin + Tizanidine Contraindicated
- Fluvoxamine + Tizanidine Contraindicated
- Pefloxacin + Tizanidine Contraindicated
- Pipemidic acid + Tizanidine Contraindicated
- Benzhydrocodone / acetaminophen + Tizanidine Major
- Brexanolone + Tizanidine Major
Other interactions of Phentolamine
Frequently asked questions
Can I take Phentolamine with Tizanidine?
MediHelp rates the interaction as moderate. Phentolamine and Tizanidine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Phentolamine blocks alpha-adrenergic receptors causing vasodilation, while tizanidine lowers sympathetic outflow centrally. Together they can cause additive hypotension and reflex tachycardia.
How serious is the interaction between Phentolamine and Tizanidine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood pressure and heart rate closely when the two are used together. Reduce the dose of one agent if significant hypotension occurs.
What other medicines interact with Tizanidine?
MediHelp also lists interactions of Tizanidine with, for example, Ciprofloxacin, Fluvoxamine, Pefloxacin. The full list is on the Tizanidine page.
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