Drug interactions
Chlorothiazide + Olmesartan
Severity: Moderate
Chlorothiazide and Olmesartan: 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
Chlorothiazide adds to olmesartan's blood pressure reduction, and the ARB offsets thiazide potassium loss. Hypotension, volume depletion and renal function changes can occur at initiation.
What this interaction means in plain words
Chlorothiazide and Olmesartan 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.
Chlorothiazide belongs to Cardiovascular; Olmesartan belongs to Cardiovascular.
Why it happens
Additive antihypertensive effects, with diuretic-induced renin activation blocked by the ARB and potassium effects offsetting each other.
What to do
Monitor blood pressure, electrolytes and creatinine after starting or adjusting either drug. Use lower initial doses in volume-depleted patients.
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 Olmesartan
- Aliskiren + Olmesartan Contraindicated
- Olmesartan + Sparsentan Contraindicated
- Aldesleukin + Olmesartan Major
- Amifostine + Olmesartan Major
- Amiloride + Olmesartan Major
- Amlodipine-benazepril + Olmesartan Major
Other interactions of Chlorothiazide
Frequently asked questions
Can I take Chlorothiazide with Olmesartan?
MediHelp rates the interaction as moderate. Chlorothiazide and Olmesartan 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. Chlorothiazide adds to olmesartan's blood pressure reduction, and the ARB offsets thiazide potassium loss. Hypotension, volume depletion and renal function changes can occur at initiation.
How serious is the interaction between Chlorothiazide and Olmesartan?
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, electrolytes and creatinine after starting or adjusting either drug. Use lower initial doses in volume-depleted patients.
What other medicines interact with Olmesartan?
MediHelp also lists interactions of Olmesartan with, for example, Aliskiren, Sparsentan, Aldesleukin. The full list is on the Olmesartan page.
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