Drug interactions
Lithium + Methyclothiazide
Severity: Major
Lithium and Methyclothiazide: major interaction.
Last updated Sources: US FDA label
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
Thiazide diuretics reduce renal lithium clearance and can substantially increase serum lithium levels. This can lead to lithium toxicity, particularly in the first weeks of therapy or with volume depletion.
What this interaction means in plain words
Lithium and Methyclothiazide 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.
Why it happens
Thiazide-induced sodium depletion increases proximal tubular reabsorption of lithium, reducing its renal clearance.
What to do
Avoid if possible. If necessary, reduce the lithium dose and monitor serum levels closely after starting, stopping or changing the diuretic.
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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References
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 Methyclothiazide?
MediHelp rates the interaction as major. Lithium and Methyclothiazide 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. Thiazide diuretics reduce renal lithium clearance and can substantially increase serum lithium levels. This can lead to lithium toxicity, particularly in the first weeks of therapy or with volume depletion.
How serious is the interaction between Lithium and Methyclothiazide?
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 if possible. If necessary, reduce the lithium dose and monitor serum levels closely after starting, stopping or changing the diuretic.
What other medicines interact with Lithium?
MediHelp also lists interactions of Lithium with, for example, Thioridazine, Vandetanib, Aceclofenac. The full list is on the Lithium page.
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