Two medicines, side by side
Carbamazepine vs zonisamide
Carbamazepine and zonisamide are both labeled for seizures and epilepsy. Drugs@FDA records approvals of carbamazepine since 1968 and of zonisamide since 2000. Pharmacies paid $0.119 per carbamazepine 200 mg tablet and $0.106 per zonisamide 100 mg capsule (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. Zonisamide's other strengths are brand-only: $2.75 per mL (Zonisade 100 mg/5 mL oral suspension). In FDA's classes, carbamazepine is a mood stabilizer and zonisamide an anti-epileptic agent.
Check it at the source: the carbamazepine FDA label on DailyMed (effective August 20, 2026); the zonisamide FDA label on DailyMed (effective June 4, 2026).
Highlights of the carbamazepine record
Carbamazepine (Tegretol) · label of August 20, 2026
SERIOUS DERMATOLOGIC REACTIONS AND HLA-B*1502 ALLELE SERIOUS AND SOMETIMES FATAL DERMATOLOGIC REACTIONS, INCLUDING TOXIC EPIDERMAL NECROLYSIS (TEN) AND STEVENS-JOHNSON SYNDROME (SJS), HAVE BEEN REPORTED DURING TREATMENT WITH TEGRETOL. THESE REACTIONS ARE ESTIMATED TO OCCUR IN 1 TO 6 PER 10,000 NEW USERS IN COUNTRIES WITH MAINLY CAUCASIAN POPULATIONS, BUT THE RISK IN SOME ASIAN COUNTRIES IS ESTIMATED TO BE ABOUT 10 TIMES HIGHER.
Used for
From the label: indicationsEpilepsy Tegretol is indicated for use as an anticonvulsant drug. Evidence supporting efficacy of Tegretol as an anticonvulsant was derived from active drug-controlled studies that enrolled patients with the following seizure types: Partial seizures with complex symptomatology (psychomotor, temporal lobe). Patients with these seizures appear to show greater improvement than those with other types. […]
On the market
- Earliest approval on file
- March 11, 1968
- Generic labelers
- 42 labelers
- Pharmacy cost
- $0.119 per tablet
Supply and safety
- Shortage
- A presentation being discontinued
- Recalls
- 11
Highlights of the zonisamide record
Zonisamide (Zonegran) · label of June 4, 2026
Used for
From the label: indicationsZonisamide is indicated as adjunctive therapy in the treatment of partial seizures in adults with epilepsy.
On the market
- Earliest approval on file
- March 27, 2000
- Generic labelers
- 20 labelers
- Pharmacy cost
- $0.106 per capsule
Supply and safety
- Shortage
- No current entry
- Recalls
- 11
Source: FDA drug labels via openFDA (Carbamazepine label of August 20, 2026, Zonisamide label of June 4, 2026); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do carbamazepine and zonisamide differ on the record?
In FDA's classes, carbamazepine is a mood stabilizer and zonisamide an anti-epileptic agent.
Half-life, in each label's words: Carbamazepine, “Initial half-life values range from 25 to 65 hours, decreasing to 12 to 17 hours on repeated doses.”; Zonisamide, “The elimination half-life of zonisamide in plasma is approximately 63 hours.”
Only the carbamazepine label carries a boxed warning.
Generics: carbamazepine since 1986; zonisamide since 2005 (Drugs@FDA).
| Carbamazepine | Zonisamide | |
|---|---|---|
| Labeled for | Bipolar disorder, Seizures and epilepsy | Seizures and epilepsy |
| Pharmacologic class | Mood Stabilizer | Anti-epileptic Agent |
| How it works (label) | Mechanism of Action Tegretol has demonstrated anticonvulsant properties in rats and mice with electrically and chemically induced seizures. It appears to act by reducing polysynaptic responses and blocking the post-tetanic potentiation. | n/a |
| Half-life (label) | Initial half-life values range from 25 to 65 hours, decreasing to 12 to 17 hours on repeated doses. | The elimination half-life of zonisamide in plasma is approximately 63 hours. |
| Earliest approval on file (Drugs@FDA) | March 11, 1968 | March 27, 2000 |
| First generic approved | August 14, 1986 | December 22, 2005 |
| Generic labelers (NDC) | 42 labelers | 20 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.119 per tablet (Carbamazepine 200 mg tablet) | $0.106 per capsule (Zonisamide 100 mg capsule) |
| 12-month price change | +0.6% | -1% |
| Boxed warning | Yes | No |
| Shortage now | A presentation being discontinued | No current entry |
| Recalls recorded | 11 | 11 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 66,615 | 10,560 |
| DEA schedule | none | none |
Source: Drugs@FDA, FDA NDC Directory, CMS NADAC of October 7, 2026, FDA shortages and recalls, FAERS via openFDA (FDA files October 8, 2026)
Do their labels mention each other?
Carbamazepine label, drug interactions… topiramate, tramadol, trazodone, tricyclic antidepressants (e.g., imipramine, amitriptyline, nortriptyline), valproate, warfarin, ziprasidone, zonisamide.
Carbamazepine label, drug interactions… triazolam, trazodone (4), tricyclic antidepressants (e.g., imipramine, amitriptyline, nortriptyline), valproate, warfarin (5), ziprasidone, and zonisamide. (2) Concomitant use of Carbatrol with hormonal contraceptive products (e.g., oral and levonorgestrel subdermal implant contraceptives) may render the contraceptives less effective because the plasma concentrations of the hormones may be decreased.
Source: FDA drug labels via openFDA
What next?
- Alternatives to carbamazepine
- every medicine labeled for the same conditions