Chlorthalidone and Lithium Carbonate: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Chlorthalidone
Lithium Carbonate
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased lithium concentrations and lithium toxicity (weakness, tremor, excessive thirst, confusion)
Interaction Deep Dive
Concurrent use of lithium and thiazide diuretics results in elevated serum levels of lithium67 due to reabsorption of sodium and lithium ions at the proximal renal tubule 89. Decreased lithium renal clearance and increases the risk of lithium toxicity 2. Consider initiating lithium at lower doses and titrating slowly while frequently monitoring serum lithium levels and for signs of lithium toxicity 1.
Why it happens (mechanism)
Decreased lithium clearance
Literature reports
3 reports — tap to read
a) Concomitant administration of lithium with either furosemide or hydrochlorothiazide in six healthy volunteers resulted in an increase in lithium levels when coadministered with hydrochlorothiazide but not furosemide. The subjects received lithium 300 mg three times daily for nine days, furosemide 40 mg daily plus lithium for 14 days, lithium alone for seven days, and lithium plus hydrochlorothiazide 50 mg daily for 14 days. Serum lithium was measured intermittently throughout the 44-day study. Of the six subjects, one withdrew after developing adverse effects during the lithium-only portion of the study. During coadministration of lithium with hydrochlorothiazide, serum lithium levels rose significantly compared to the lithium-only phase and the lithium plus furosemide phase. The authors suggested that patients given thiazide diuretics may need a downward adjustment of their lithium dosage to maintain acceptable serum lithium levels 3.
b) A 60-year old woman developed lithium toxicity after the addition of a thiazide diuretic to control hypertension. The patient had taken lithium 600 mg twice daily and maintained serum lithium levels of 0.8 mEq/L to 1.2 mEq/L. Two weeks after hydrochlorothiazide 50 mg daily was added to the patient's regimen, she developed insomnia, confusion, tremor, muscle fasciculations, dysarthria, and ataxia. The patient's serum lithium level was measured at 3.9 mEq/L. After hemodialysis, the patient's lithium level was 1.4 mEq/L but mental status continued to deteriorate. The patient's condition gradually improved over the next five days with osmotic diuresis and supportive treatment 4.
c) A case of severe lithium toxicity (diarrhea, dyspnea, drowsiness, confusion, peripheral vasodilatation, and hyperreflexia) in a 51-year old non-insulin dependent female patient with diabetes was reportedly caused by a thiazide diuretic and an angiotensin converting enzyme inhibitor 5. Lithium carbonate 1.6 grams daily had been given for seven years for manic depression, as well as glibenclamide 5 mg daily (18 months). Perindopril 8 mg daily and bendrofluazide 5 mg daily had been added for hypertension three months prior to presentation. Diarrhea, dyspnea, confusion, and hypotension developed over a two-week period. Her lithium level was 4.28 mmol/L on admission to the hospital, and her blood pressure was 80/60 mmHg. Dopamine and dobutamine were started but were not effective. Her blood pressure was eventually maintained with norepinephrine, epinephrine, and dobutamine at doses normally associated with marked alpha-adrenoceptor-mediated vasoconstriction. The patient became more alert when the lithium level dropped to 1.6 mmol/L following three hemodialysis sessions, and cardiovascular support was then withdrawn.
Common questions
Can I take Chlorthalidone and Lithium Carbonate together?
Increased lithium concentrations and lithium toxicity (weakness, tremor, excessive thirst, confusion) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Chlorthalidone and Lithium Carbonate interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Chlorthalidone or Lithium Carbonate need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (9)
- Product Information: Lithium carbonate oral tablets, oral capsules, lithium carbonate oral tablets, oral capsules. West-Ward Pharmaceuticals Corp (per FDA), Eatontown, NJ, 2018. DailyMed
- Product Information: THALITONE(R) oral tablets, chlorthalidone oral tablets. Casper Pharma LLC (per FDA), East Brunswick, NJ, 2019. DailyMed
- Jefferson JW & Kalin NH: Serum lithium levels and long-term diuretic use. JAMA 1979; 241:1134-1136. DOI
- Nurnberger JI Jr: Diuretic-induced lithium toxicity presenting as mania. J Nerv Ment Dis 1985; 173:316-318. PubMed
- Vipond AJ, Bakewell S, Telford R, et al: Lithium toxicity. Anaesthesia 1996; 51:1156-1158.
- Product Information: Eskalith(R), lithium carbonate. GlaxoSmithKline, Research Triangle Park, NC, 2003. DailyMed
- Petersen V, Hvidt S, Thomsen K, et al: Effect of prolonged thiazide treatment on renal lithium clearance. Br Med J 1974; 3:143-145. PubMed
- Singer I & Rotenberg P: Mechanisms of lithium action. N Engl J Med 1973; 289:254. DOI
- Davis JM & Fann WE: Lithium. Ann Rev Pharmacol 1971; 11:285.
Keep reading about Chlorthalidone
Keep reading about Lithium Carbonate
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