Lamotrigine and Nirmatrelvir and ritonavir interaction
Lamotrigine and Nirmatrelvir and ritonavir: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Nirmatrelvir and ritonavir (Paxlovid) label · effective 2026-02-19
…of the following medications due to the delayed offset of the recently discontinued CYP3A inducer [see Drug Interactions (7.3) ] : • Anticancer drugs: apalutamide, enzalutamide • Anticonvulsant: carbamazepine, phenobarbital, primidone, phenytoin • Antimycobacterials: rifampin, rifapentine • Cystic fibrosis transmembrane conductance regulator potentiators: lumacaftor/ivacaftor…
Anticonvulsants carbamazepine , phenobarbital, primidone, phenytoin ↓ nirmatrelvir/ritonavir Co-administration contraindicated due to potential loss of virologic response and possible resistance [see Contraindications (4) ] .
Anticonvulsants clonazepam ↑ anticonvulsant A dose decrease may be needed for clonazepam when co-administered with PAXLOVID and clinical monitoring is recommended.
From the Lamotrigine (SUBVENITE) label · effective 2026-06-04
Protease inhibitors lopinavir/ritonavir and atazanavir/lopinavir decrease lamotrigine exposure by approximately 50% and 32%, respectively.
Lopinavir/ritonavir ↓ lamotrigine Decreased lamotrigine concentration approximately 50%.
Atazanavir/ritonavir ↓ lamotrigine Decreased lamotrigine AUC approximately 32%.
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.