What the FDA labels say about taking them together
Lamotrigine and rifampin
Lamotrigine's FDA label of October 10, 2025 names rifampin in its drug interactions section; the rifampin label PlainMeds reads does not name lamotrigine. The lamotrigine label: “Decreased lamotrigine AUC approximately 40%.”
Check it at the source: the lamotrigine FDA label on DailyMed (effective October 10, 2025); the rifampin FDA label on DailyMed (effective February 11, 2026, Lupin Pharmaceuticals, Inc.).
What does the lamotrigine label say about rifampin?
Lamotrigine label, drug interactionsConcomitant Drug: Rifampin; Effect on Concentration of Lamotrigine or Concomitant Drug: ↓ lamotrigine; Clinical Comment: Decreased lamotrigine AUC approximately 40%.
Subvenite label (OWP Pharmaceuticals, Inc., June 4, 2026), drug interactionsDRUG INTERACTIONS Valproate increases lamotrigine concentrations more than 2-fold. ( 7 , 12.3 ) Carbamazepine, phenytoin, phenobarbital, primidone, and rifampin decrease lamotrigine concentrations by approximately 40%. ( 7 , 12.3 ) Estrogen-containing oral contraceptives decrease lamotrigine concentrations by approximately 50%. ( 7 , 12.3 ) Protease inhibitors lopinavir/ritonavir and atazanavir/lopinavir decrease lamotrigine exposure by approximately 50% and 32%, respectively. ( 7 , 12.3 ) Coadministration with organic cationic transporter 2 substrates with narrow therapeutic index is not recommended ( 7 , 12.3 ) Significant drug interactions with SUBVENITE are summarized in this section.
Source: FDA drug label (Subvenite, NDA218879), OWP Pharmaceuticals, Inc., effective June 4, 2026 (SPL set 022b0913-f683-4af8-a862-f81b315909b2), via openFDA
Source: FDA drug label (LAMICTAL), GlaxoSmithKline LLC, effective October 10, 2025 (SPL set d7e3572d-56fe-4727-2bb4-013ccca22678), via openFDA; the full label on DailyMed
What does the rifampin label say about lamotrigine?
Rifampin's label (effective February 11, 2026) does not name lamotrigine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (rifampin), Lupin Pharmaceuticals, Inc., effective February 11, 2026 (SPL set b56004f0-f23d-47f6-80c7-39884fccbccc), 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
| Lamotrigine | Rifampin | |
|---|---|---|
| Labeled for | Seizures and epilepsy, Bipolar disorder | n/a |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.0268 per tablet 25 mg tablet | $0.679 per capsule 300 mg capsule |
| Shortage now | A presentation being discontinued | In shortage |
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