Two medicines, side by side
Lamotrigine vs valproic acid
Lamotrigine and valproic acid are both labeled for seizures and epilepsy. Drugs@FDA records approvals of lamotrigine since 1994 and of valproic acid since 1978. Pharmacies paid $0.0268 per lamotrigine 25 mg tablet and $0.243 per valproic acid 250 mg capsule (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. Lamotrigine's other strengths are brand-only: $2.86 per mL (Subvenite 10 mg/mL suspension). How each works, in its label's words: Lamotrigine, “The precise mechanism(s) by which lamotrigine exerts its anticonvulsant action are unknown.”; Valproic acid, “Valproic acid dissociates to the valproate ion in the gastrointestinal tract.”
Check it at the source: the lamotrigine FDA label on DailyMed (effective October 10, 2025); the valproic acid FDA label on DailyMed (effective January 24, 2025).
Highlights of the lamotrigine record
Lamotrigine (Lamictal) · label of October 10, 2025
SERIOUS SKIN RASHES LAMICTAL can cause serious rashes requiring hospitalization and discontinuation of treatment. The incidence of these rashes, which have included Stevens-Johnson syndrome, is approximately 0.3% to 0.8% in pediatric patients (aged 2 to 17 years) and 0.08% to 0.3% in adults receiving LAMICTAL. One rash-related death was reported in a prospectively followed cohort of 1,983 pediatric patients (aged 2 to 16 years) with epilepsy taking LAMICTAL as adjunctive therapy.
Used for
From the label: indicationsLAMICTAL is indicated for: Epilepsy–adjunctive therapy in patients aged 2 years and older: • partial-onset seizures. • primary generalized tonic-clonic (PGTC) seizures. • generalized seizures of Lennox-Gastaut syndrome. […]
On the market
- Earliest approval on file
- December 27, 1994
- Generic labelers
- 49 labelers
- Pharmacy cost
- $0.0268 per tablet
Supply and safety
- Shortage
- A presentation being discontinued
- Recalls
- 10
Highlights of the valproic acid record
Valproic acid (Depakene) · label of January 24, 2025
LIFE THREATENING ADVERSE REACTIONS WARNING: LIFE THREATENING ADVERSE REACTIONS See full prescribing information for complete boxed warning. Hepatotoxicity, including fatalities, usually during the first 6 months of treatment. Children under the age of two years and patients with mitochondrial disorders are at higher risk.
Used for
From the label: indicationsValproic acid is indicated for: Monotherapy and adjunctive therapy of complex partial seizures; sole and adjunctive therapy of simple and complex absence seizures; adjunctive therapy in patients with multiple seizure types that include absence seizures ( 1 ) 1.1 Epilepsy Valproic acid is indicated as monotherapy and adjunctive therapy in the treatment of patients with complex partial seizures that occur either in isolation or in association with other types of seizures. […]
On the market
- Earliest approval on file
- February 28, 1978
- Generic labelers
- 22 labelers
- Pharmacy cost
- $0.243 per capsule
Supply and safety
- Shortage
- Listed; available
- Recalls
- 2
Source: FDA drug labels via openFDA (Lamotrigine label of October 10, 2025, Valproic acid label of January 24, 2025); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do lamotrigine and valproic acid differ on the record?
How each works, in its label's words: Lamotrigine, “The precise mechanism(s) by which lamotrigine exerts its anticonvulsant action are unknown.”; Valproic acid, “Valproic acid dissociates to the valproate ion in the gastrointestinal tract.”
Both are in FDA's class mood stabilizers.
Both labels carry a boxed warning; the records quote them.
Generics: lamotrigine since 2006; valproic acid since 1986 (Drugs@FDA).
| Lamotrigine | Valproic acid | |
|---|---|---|
| Labeled for | Seizures and epilepsy, Bipolar disorder | Seizures and epilepsy, Migraine |
| Pharmacologic class | Anti-epileptic Agent, Mood Stabilizer | Anti-epileptic Agent, Mood Stabilizer |
| How it works (label) | The precise mechanism(s) by which lamotrigine exerts its anticonvulsant action are unknown. | Valproic acid dissociates to the valproate ion in the gastrointestinal tract. The mechanisms by which valproate exerts its therapeutic effects have not been established. |
| Half-life (label) | n/a | Mean terminal half-life for valproate monotherapy ranged from 9 to 16 hours following oral dosing regimens of 250 to 1,000 mg. |
| Earliest approval on file (Drugs@FDA) | December 27, 1994 | February 28, 1978 |
| First generic approved | June 21, 2006 | February 28, 1986 |
| Generic labelers (NDC) | 49 labelers | 22 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.0268 per tablet (Lamotrigine 25 mg tablet) | $0.243 per capsule (Valproic acid 250 mg capsule) |
| 12-month price change | -12% | -4% |
| Boxed warning | Yes | Yes |
| Shortage now | A presentation being discontinued | Listed; available |
| Recalls recorded | 10 | 2 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 130,994 | 51,380 |
| 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?
Valproic acid label, warnings and precautionsThe largest of these studies 1 is a prospective cohort study conducted in the United States and United Kingdom that found that children with prenatal exposure to valproate (n=62) had lower IQ scores at age 6 (97 [95% C.I. 94-101]) than children with prenatal exposure to the other antiepileptic drug monotherapy treatments evaluated: lamotrigine (108 [95% C.I. 105-110]), carbamazepine (105 [95% C.I. …
Source: FDA drug labels via openFDA
What next?
- Alternatives to lamotrigine
- every medicine labeled for the same conditions