Drug interactions
Diltiazem + Prazosin
Severity: Moderate
Diltiazem and Prazosin: 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
Both drugs lower blood pressure, so combined use can cause excessive hypotension, dizziness and syncope, especially after the first dose of prazosin. Diltiazem may also slightly raise prazosin exposure.
What this interaction means in plain words
Diltiazem and Prazosin 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.
Diltiazem belongs to Cardiovascular; Prazosin belongs to Genitourinary.
Why it happens
Additive vasodilatory and blood-pressure-lowering effects through alpha-1 blockade and calcium channel blockade.
What to do
Start prazosin at a low dose at bedtime and titrate slowly. Monitor blood pressure and orthostatic symptoms.
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 Diltiazem
- Diltiazem + Flibanserin Contraindicated
- Diltiazem + Ivabradine Contraindicated
- Diltiazem + Lomitapide Contraindicated
- Diltiazem + Lonafarnib Contraindicated
- Acebutolol + Diltiazem Major
- Alfentanil + Diltiazem Major
Other interactions of Prazosin
- Alfuzosin + Prazosin Major
- Amifostine + Prazosin Major
- Avanafil + Prazosin Major
- Doxazosin + Prazosin Major
- Dutasteride-tamsulosin + Prazosin Major
- Phenoxybenzamine + Prazosin Major
Frequently asked questions
Can I take Diltiazem with Prazosin?
MediHelp rates the interaction as moderate. Diltiazem and Prazosin 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. Both drugs lower blood pressure, so combined use can cause excessive hypotension, dizziness and syncope, especially after the first dose of prazosin. Diltiazem may also slightly raise prazosin exposure.
How serious is the interaction between Diltiazem and Prazosin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Start prazosin at a low dose at bedtime and titrate slowly. Monitor blood pressure and orthostatic symptoms.
What other medicines interact with Diltiazem?
MediHelp also lists interactions of Diltiazem with, for example, Flibanserin, Ivabradine, Lomitapide. The full list is on the Diltiazem page.
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