Two medicines, side by side
Carbamazepine vs phenytoin
Carbamazepine and phenytoin are both labeled for seizures and epilepsy. Drugs@FDA records approvals of carbamazepine since 1968 and of phenytoin since 1953. Pharmacies paid $0.119 per carbamazepine 200 mg tablet and $0.145 per phenytoin sod ext 100 mg capsule (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. In FDA's classes, carbamazepine is a mood stabilizer and phenytoin an anti-epileptic agent.
Check it at the source: the carbamazepine FDA label on DailyMed (effective August 20, 2026); the phenytoin FDA label on DailyMed (effective October 15, 2024).
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 phenytoin record
Phenytoin (Dilantin) · label of October 15, 2024
Used for
From the label: indicationsPHENYTEK ® capsules (extended phenytoin sodium capsules) are indicated for the treatment of tonic-clonic (grand mal) and psychomotor (temporal lobe) seizures and prevention and treatment of seizures occurring during or following neurosurgery. […]
On the market
- Earliest approval on file
- January 6, 1953
- Generic labelers
- 29 labelers
- Pharmacy cost
- $0.145 per capsule
Supply and safety
- Shortage
- No current entry
- Recalls
- 11
Source: FDA drug labels via openFDA (Carbamazepine label of August 20, 2026, Phenytoin label of October 15, 2024); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do carbamazepine and phenytoin differ on the record?
In FDA's classes, carbamazepine is a mood stabilizer and phenytoin an anti-epileptic agent.
How each works, in its label's words: Carbamazepine, “It appears to act by reducing polysynaptic responses and blocking the post-tetanic potentiation.”; Phenytoin, “The precise mechanism by which phenytoin exerts its therapeutic effect has not been established but is thought to involve the voltage-dependent blockade of membrane sodium channels resulting in a …”
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.”; Phenytoin, “Elimination The plasma half-life in man after oral administration of phenytoin averages 22 hours, with a range of 7 to …”
Only the carbamazepine label carries a boxed warning.
Generics: carbamazepine since 1986; phenytoin since 1975 (Drugs@FDA).
| Carbamazepine | Phenytoin | |
|---|---|---|
| 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. | The precise mechanism by which phenytoin exerts its therapeutic effect has not been established but is thought to involve the voltage-dependent blockade of membrane sodium channels resulting in a reduction in sustained high-frequency … |
| Half-life (label) | Initial half-life values range from 25 to 65 hours, decreasing to 12 to 17 hours on repeated doses. | Elimination The plasma half-life in man after oral administration of phenytoin averages 22 hours, with a range of 7 to 42 hours. |
| Earliest approval on file (Drugs@FDA) | March 11, 1968 | January 6, 1953 |
| First generic approved | August 14, 1986 | July 16, 1975 |
| Generic labelers (NDC) | 42 labelers | 29 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.119 per tablet (Carbamazepine 200 mg tablet) | $0.145 per capsule (Phenytoin sod ext 100 mg capsule) |
| 12-month price change | +0.6% | -5% |
| 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 | 40,278 |
| 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 interactionsDrugs that have been shown, or that would be expected, to decrease plasma carbamazepine levels include cisplatin, doxorubicin HCl, felbamate, fosphenytoin, rifampin, phenobarbital, phenytoin, primidone, methsuximide, theophylline, aminophylline.
Carbamazepine label, warningsLimited evidence suggests that HLA-B*1502 may be a risk factor for the development of SJS/TEN in patients of Chinese ancestry taking other antiepileptic drugs associated with SJS/TEN, including phenytoin.
Phenytoin label, drug interactionsInteracting Agent: Antiepileptic drugs; Examples: Carbamazepine, vigabatrin
Phenytoin label, warnings and precautionsStudies in patients of Chinese ancestry have found a strong association between the risk of developing SJS/TEN and the presence of HLA-B*1502, an inherited allelic variant of the HLA B gene, in patients using carbamazepine.
Source: FDA drug labels via openFDA
What next?
- Alternatives to carbamazepine
- every medicine labeled for the same conditions