Drug interactions
Hydrochlorothiazide + Metolazone
Severity: Major
Hydrochlorothiazide and Metolazone: major 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
Metolazone is a thiazide-like diuretic and combining it with hydrochlorothiazide duplicates the same action. This can cause profound diuresis with severe hypokalemia, hyponatremia, hypomagnesemia, dehydration and renal impairment.
What this interaction means in plain words
Hydrochlorothiazide and Metolazone can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Hydrochlorothiazide belongs to Cardiovascular; Metolazone belongs to Cardiovascular.
Why it happens
Both drugs inhibit the sodium-chloride cotransporter in the distal tubule, giving additive natriuresis and electrolyte loss.
What to do
Avoid combining the two unless specifically intended, and prefer a single thiazide-type agent. If combined, monitor electrolytes, renal function and weight closely.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Hydrochlorothiazide
Other interactions of Metolazone
Frequently asked questions
Can I take Hydrochlorothiazide with Metolazone?
MediHelp rates the interaction as major. Hydrochlorothiazide and Metolazone can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Metolazone is a thiazide-like diuretic and combining it with hydrochlorothiazide duplicates the same action. This can cause profound diuresis with severe hypokalemia, hyponatremia, hypomagnesemia, dehydration and renal impairment.
How serious is the interaction between Hydrochlorothiazide and Metolazone?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid combining the two unless specifically intended, and prefer a single thiazide-type agent. If combined, monitor electrolytes, renal function and weight closely.
What other medicines interact with Hydrochlorothiazide?
MediHelp also lists interactions of Hydrochlorothiazide with, for example, Dofetilide, Amifostine, Amiodarone. The full list is on the Hydrochlorothiazide page.
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