What the FDA labels say about taking them together
Acetazolamide and zonisamide
Zonisamide's FDA label (Zonegran) of September 12, 2025 names acetazolamide in its drug interactions section; the acetazolamide label PlainMeds reads does not name zonisamide. The zonisamide label: “Other Carbonic Anhydrase Inhibitors: Concomitant use of ZONEGRAN, a carbonic anhydrase inhibitor, with any other carbonic anhydrase inhibitor, may increase the severity of metabolic acidosis and may also increase the …”
Check it at the source: the acetazolamide FDA label on DailyMed (effective August 19, 2026, Strides Pharma Science Limited); the zonisamide FDA label on DailyMed (effective June 4, 2026, Sun Pharmaceutical Industries, Inc.).
What does the acetazolamide label say about zonisamide?
Acetazolamide's label (effective August 19, 2026) does not name zonisamide in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Acetazolamide), Strides Pharma Science Limited, effective August 19, 2026 (SPL set 4813b9dd-5f58-44bb-ad64-cdb331828080), via openFDA; the full label on DailyMed
What does the zonisamide label say about acetazolamide?
Zonegran label (Advanz Pharma (US) Corp., September 12, 2025), drug interactionsOther Carbonic Anhydrase Inhibitors: Concomitant use of ZONEGRAN, a carbonic anhydrase inhibitor, with any other carbonic anhydrase inhibitor (e.g., topiramate, acetazolamide or dichlorphenamide), may increase the severity of metabolic acidosis and may also increase the risk of kidney stone formation or the risk of hyperammonemia.
Source: FDA drug label (Zonegran, NDA020789), Advanz Pharma (US) Corp., effective September 12, 2025 (SPL set d12de43e-3ac3-4335-bc85-70d7366a91eb), via openFDA
Source: FDA drug label (Zonisamide), Sun Pharmaceutical Industries, Inc., effective June 4, 2026 (SPL set 3164d438-90bf-420a-9a56-5498b987f91c), 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
| Acetazolamide | Zonisamide | |
|---|---|---|
| Labeled for | n/a | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.134 per tablet 250 mg tablet | $0.106 per capsule 100 mg capsule |
| 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