What the FDA labels say about taking them together
Lithium and methyldopa
Lithium's FDA label of December 23, 2025 names methyldopa in its drug interactions section; the methyldopa label PlainMeds reads does not name lithium. The lithium label: “Concomitant use can lower serum lithium concentrations by increasing urinary lithium excretion.”
Check it at the source: the lithium FDA label on DailyMed (effective December 23, 2025, Glenmark Pharmaceuticals Inc., USA); the methyldopa FDA label on DailyMed (effective March 26, 2025, Chartwell RX, LLC).
What does the lithium label say about methyldopa?
Lithium label, drug interactionsClinical Impact: Concomitant use can lower serum lithium concentrations by increasing urinary lithium excretion. Intervention: More frequent serum lithium concentration monitoring. Increase lithium dosage based on serum lithium concentration and clinical response [see Dosage and Administration ( 2.3 )]. Methyldopa, Phenytoin and Carbamazepine
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 methyldopa label say about lithium?
Methyldopa's label (effective March 26, 2025) does not name lithium in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Methyldopa), Chartwell RX, LLC, effective March 26, 2025 (SPL set e1114a58-9ab5-486e-85ed-360365b06396), 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 | Methyldopa | |
|---|---|---|
| Labeled for | Bipolar disorder | n/a |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.104 per capsule 300 mg capsule | n/a |
| 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