Drug interactions
Captopril-hydrochlorothiazide + Phenobarbital
Severity: Moderate
Captopril-hydrochlorothiazide and Phenobarbital: 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
Phenobarbital may add to the blood pressure lowering of captopril and hydrochlorothiazide, producing hypotension or orthostatic symptoms. Phenobarbital is also an enzyme inducer, though this is of little consequence for these two drugs.
What this interaction means in plain words
Captopril-hydrochlorothiazide and Phenobarbital 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.
Why it happens
Additive hypotensive effects through CNS depression and vasodilation combined with antihypertensive action.
What to do
Monitor blood pressure, especially after starting or increasing phenobarbital. Adjust antihypertensive doses if 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 Captopril-hydrochlorothiazide
- Aliskiren + Captopril-hydrochlorothiazide Contraindicated
- Captopril-hydrochlorothiazide + Dofetilide Contraindicated
- Captopril-hydrochlorothiazide + Sacubitril / valsartan Contraindicated
- Aceclofenac + Captopril-hydrochlorothiazide Major
- Aldesleukin + Captopril-hydrochlorothiazide Major
- Amifostine + Captopril-hydrochlorothiazide Major
Frequently asked questions
Can I take Captopril-hydrochlorothiazide with Phenobarbital?
MediHelp rates the interaction as moderate. Captopril-hydrochlorothiazide and Phenobarbital 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. Phenobarbital may add to the blood pressure lowering of captopril and hydrochlorothiazide, producing hypotension or orthostatic symptoms. Phenobarbital is also an enzyme inducer, though this is of little consequence for these two drugs.
How serious is the interaction between Captopril-hydrochlorothiazide and Phenobarbital?
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, especially after starting or increasing phenobarbital. Adjust antihypertensive doses if hypotension occurs.
What other medicines interact with Captopril-hydrochlorothiazide?
MediHelp also lists interactions of Captopril-hydrochlorothiazide with, for example, Aliskiren, Dofetilide, Sacubitril / valsartan. The full list is on the Captopril-hydrochlorothiazide page.
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