What the FDA labels say about taking them together
Dofetilide and hydrochlorothiazide
Dofetilide's FDA label of April 21, 2026 names hydrochlorothiazide in its contraindications section; the hydrochlorothiazide labels PlainMeds reads (3) do not name dofetilide. The dofetilide label: “The concomitant use of hydrochlorothiazide with TIKOSYN is contraindicated because this has been shown to significantly increase dofetilide plasma concentrations and QT interval prolongation.”
Check it at the source: the dofetilide FDA label on DailyMed (effective April 21, 2026, Pfizer Laboratories Div Pfizer Inc); the hydrochlorothiazide FDA label on DailyMed (effective June 12, 2026, Leading Pharma, LLC).
What does the dofetilide label say about hydrochlorothiazide?
Dofetilide label, contraindicationsThe concomitant use of hydrochlorothiazide (alone or in combinations such as with triamterene) with TIKOSYN is contraindicated (see PRECAUTIONS, Drug-Drug Interactions ) because this has been shown to significantly increase dofetilide plasma concentrations and QT interval prolongation.
Source: FDA drug label (Tikosyn), Pfizer Laboratories Div Pfizer Inc, effective April 21, 2026 (SPL set 02438044-d6a3-49e9-a1ac-3aad21ef2c8c), via openFDA; the full label on DailyMed
What does the hydrochlorothiazide label say about dofetilide?
Hydrochlorothiazide's label (effective June 12, 2026) and its 2 other brand-application labels do not name dofetilide in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (HYDROCHLOROTHIAZIDE), Leading Pharma, LLC, effective June 12, 2026 (SPL set 8c868894-667e-4a51-906a-838d63e420ba), 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
| Dofetilide | Hydrochlorothiazide | |
|---|---|---|
| Labeled for | Atrial fibrillation | Heart failure, High blood pressure, Edema (fluid retention) |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.203 per capsule 125 mcg capsule | $0.0115 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