What the FDA labels say about taking them together
Digoxin and spironolactone
Digoxin's FDA label of December 5, 2024 names spironolactone in its drug interactions section, and spironolactone's label names digoxin too. The spironolactone label: “ALDACTONE can interfere with radioimmunologic assays of digoxin exposure.”
Check it at the source: the digoxin FDA label on DailyMed (effective December 5, 2024, Advanz Pharma (US) Corp.); the spironolactone FDA label on DailyMed (effective November 28, 2025, Pfizer Laboratories Div Pfizer Inc).
What does the digoxin label say about spironolactone?
Digoxin label, drug interactionsSpironolactone; 25%; NA; Measure serum digoxin concentrations before initiating concomitant drugs. Reduce digoxin concentrations by decreasing the dose by approximately 15-30% or by modifying the dosing frequency and continue monitoring.
Source: FDA drug label (Digoxin, NDA021648), Hikma Pharmaceuticals USA Inc., effective April 10, 2025 (SPL set 1b7e5c6e-e052-41b0-a4ce-05dfe62faaaf), via openFDA
Source: FDA drug label (Lanoxin, NDA009330), Covis Pharma US, Inc, effective October 17, 2025 (SPL set 9ec84cac-6ecc-43dc-8006-6ccc029e2707), via openFDA
Source: FDA drug label (LANOXIN), Advanz Pharma (US) Corp., effective December 5, 2024 (SPL set d91e3646-4c63-4512-ab22-db39c085c4dc), via openFDA; the full label on DailyMed
What does the spironolactone label say about digoxin?
Spironolactone label, drug interactionsALDACTONE can interfere with radioimmunologic assays of digoxin exposure ( 7.4 ).
Spironolactone label (Atlantic Biologicals Corp., August 28, 2026), drug interactionsIncreased risk of lithium toxicity ( 7.2 ) NSAIDs: May reduce the diuretic, natriuretic and antihypertensive effect of spironolactone oral suspension ( 7.3 ) Digoxin:
Source: FDA drug label (Spironolactone, NDA209478), Atlantic Biologicals Corp., effective August 28, 2026 (SPL set 5a203ae4-0ed1-0099-e063-6294a90abc85), via openFDA
Source: FDA drug label (Aldactone), Pfizer Laboratories Div Pfizer Inc, effective November 28, 2025 (SPL set 0fed2822-3a03-4b64-9857-c682fcd462bc), 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
| Digoxin | Spironolactone | |
|---|---|---|
| Labeled for | Heart failure, Atrial fibrillation | Heart failure, Edema (fluid retention), High blood pressure |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.133 per tablet 125 mcg tablet | $0.0426 per tablet 25 mg tablet |
| Shortage now | No current entry | A presentation being discontinued |
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