What the FDA labels say about taking them together
Ensitrelvir and quinidine
Ensitrelvir's FDA label of June 3, 2026 names quinidine in its drug interactions section; the quinidine label PlainMeds reads does not name ensitrelvir. The ensitrelvir label: “Co-administration is contraindicated due to potential for cardiac arrhythmias.”
Check it at the source: the ensitrelvir FDA label on DailyMed (effective June 3, 2026, Shionogi Inc.); the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.).
What does the ensitrelvir label say about quinidine?
Ensitrelvir label, drug interactionsDrug Class: Antiarrhythmics; Drug (s) within Class: quinidine; Effect on Drug Concentration: ↑ antiarrhythmic; Clinical Comment: Co-administration is contraindicated due to potential for cardiac arrhythmias.
Source: FDA drug label (XOCOVA), Shionogi Inc., effective June 3, 2026 (SPL set 526acf60-abc3-2cc2-e063-6294a90affa6), via openFDA; the full label on DailyMed
What does the quinidine label say about ensitrelvir?
Quinidine's label (effective February 1, 2018) does not name ensitrelvir in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Quinidine Gluconate), Sun Pharmaceutical Industries, Inc., effective February 1, 2018 (SPL set 5023f053-fcc4-4c2c-aa59-9ec198ad185e), 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
| Ensitrelvir | Quinidine | |
|---|---|---|
| Labeled for | COVID-19 | Atrial fibrillation |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $4.92 per tablet 324 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