Drug interactions
Lithium + Metolazone
Severity: Major
Lithium 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 can reduce renal lithium clearance and raise serum lithium concentrations. This can lead to lithium toxicity with tremor, confusion, ataxia, gastrointestinal upset and, in severe cases, seizures or renal injury.
What this interaction means in plain words
Lithium 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.
Lithium belongs to Central Nervous System; Metolazone belongs to Cardiovascular.
Why it happens
Sodium depletion from the diuretic increases proximal tubular reabsorption of lithium, lowering its renal clearance.
What to do
Avoid the combination where possible; if used, reduce the lithium dose and check serum lithium levels within the first week and after any diuretic dose change. Counsel the patient to recognise early toxicity signs and maintain hydration and sodium intake.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Lithium and Metolazone, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Metolazone
Other interactions of Lithium
- Lithium + Thioridazine Contraindicated
- Lithium + Vandetanib Contraindicated
- Aceclofenac + Lithium Major
- Acemetacin + Lithium Major
- Amisulpride + Lithium Major
- Amlodipine-benazepril + Lithium Major
Frequently asked questions
Can I take Lithium with Metolazone?
MediHelp rates the interaction as major. Lithium 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 can reduce renal lithium clearance and raise serum lithium concentrations. This can lead to lithium toxicity with tremor, confusion, ataxia, gastrointestinal upset and, in severe cases, seizures or renal injury.
How serious is the interaction between Lithium 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 the combination where possible; if used, reduce the lithium dose and check serum lithium levels within the first week and after any diuretic dose change. Counsel the patient to recognise early toxicity signs and maintain hydration and sodium intake.
What other medicines interact with Metolazone?
MediHelp also lists interactions of Metolazone with, for example, Amifostine, Amlodipine-hydrochlorothiazide-valsartan, Amlodipine-olmesartan-hydrochlorothiazide. The full list is on the Metolazone page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
