What the FDA labels say about taking them together
Lithium and metolazone
Metolazone's FDA label of December 11, 2025 names lithium in its drug interactions section; the lithium labels PlainMeds reads (4) do not name metolazone. The metolazone label: “Lithium Serum lithium levels may increase (see WARNINGS).”
Check it at the source: the lithium FDA label on DailyMed (effective December 23, 2025, Glenmark Pharmaceuticals Inc., USA); the metolazone FDA label on DailyMed (effective December 11, 2025, Unichem Pharmaceuticals (USA), Inc.).
What does the lithium label say about metolazone?
Lithium's label (effective December 23, 2025) and its 3 other brand-application labels do not name metolazone in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Lithium Carbonate), Glenmark Pharmaceuticals Inc., USA, effective December 23, 2025 (SPL set 63b3790f-a9b5-47f4-bae1-ddf8b43c13c1), via openFDA; the full label on DailyMed
What does the metolazone label say about lithium?
Metolazone label, drug interactionsLithium Serum lithium levels may increase (see WARNINGS).
Metolazone label, warningsConcomitant Therapy Lithium In general, diuretics should not be given concomitantly with lithium because they reduce its renal clearance and add a high risk of lithium toxicity.
Source: FDA drug label (Metolazone), Unichem Pharmaceuticals (USA), Inc., effective December 11, 2025 (SPL set c6fe5426-a184-44b8-a555-621d72aa5b9f), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Lithium | Metolazone | |
|---|---|---|
| Labeled for | Bipolar disorder | High blood pressure, Edema (fluid retention), Heart failure |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.104 per capsule 300 mg capsule | $0.233 per tablet 2.5 mg tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once