What the FDA labels say about taking them together
Ethosuximide and ritonavir
Ritonavir's FDA label of July 23, 2026 names ethosuximide in its drug interactions section; the ethosuximide labels PlainMeds reads (2) do not name ritonavir. The ritonavir label: “A dose decrease may be needed for these drugs when co-administered with ritonavir and therapeutic concentration monitoring is recommended for these anticonvulsants, if available.”
Check it at the source: the ethosuximide FDA label on DailyMed (effective June 11, 2026, Chartwell Governmental & Specialty RX, LLC.); the ritonavir FDA label on DailyMed (effective July 23, 2026, AbbVie Inc.).
What does the ethosuximide label say about ritonavir?
Ethosuximide's label (effective June 11, 2026) and its 1 other brand-application label do not name ritonavir in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Ethosuximide), Chartwell Governmental & Specialty RX, LLC., effective June 11, 2026 (SPL set a825265d-ace9-4463-a16d-f6d5e1e31188), via openFDA; the full label on DailyMed
What does the ritonavir label say about ethosuximide?
Ritonavir label, drug interactionsConcomitant Drug Class/Drug Name: Anticonvulsants: carbamazepine, clonazepam, ethosuximide; Effect on Concentration of Ritonavir or Concomitant Drug: ↑ anticonvulsants; Clinical Comment: A dose decrease may be needed for these drugs when co-administered with ritonavir and therapeutic concentration monitoring is recommended for these anticonvulsants, if available.
Source: FDA drug label (Norvir), AbbVie Inc., effective July 23, 2026 (SPL set 2849298e-de6e-47bb-8194-56e075b33fc3), 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
| Ethosuximide | Ritonavir | |
|---|---|---|
| Labeled for | Seizures and epilepsy | HIV |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.243 per capsule 250 mg capsule | $0.607 per tablet 100 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