What the FDA labels say about taking them together
Doxepin and quinidine
Doxepin's FDA label (Prudoxin) of June 29, 2017 names quinidine in its drug interactions section; the quinidine label PlainMeds reads does not name doxepin.
Check it at the source: the doxepin FDA label on DailyMed (effective December 30, 2025, Leading Pharma, LLC); the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.).
What does the doxepin label say about quinidine?
Prudoxin label (Mylan Pharmaceuticals Inc., June 29, 2017), drug interactionsThe drugs that inhibit cytochrome P450 2D6 include some that are not metabolized by the enzyme (quinidine; cimetidine) and many that are substrates for P450 2D6 (many other antidepressants, phenothiazines, and the Type 1C antiarrhythmics propafenone and flecainide).
Source: FDA drug label (Prudoxin, NDA020126), Mylan Pharmaceuticals Inc., effective June 29, 2017 (SPL set ca53346b-8ab3-4722-98f6-cf272706d3fa), via openFDA
Source: FDA drug label (DOXEPIN HYDROCHLORIDE), Leading Pharma, LLC, effective December 30, 2025 (SPL set e6a4cb10-1928-4abe-8797-404c9ddc37dd), via openFDA; the full label on DailyMed
What does the quinidine label say about doxepin?
Quinidine's label (effective February 1, 2018) does not name doxepin 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
| Doxepin | Quinidine | |
|---|---|---|
| Labeled for | Depression, Anxiety, Eczema (atopic dermatitis), Insomnia | Atrial fibrillation |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.0779 per capsule 10 mg capsule | $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