* Abrupt stop of carbamazepine can cause serious lamotrigine rash as lamotrigine levels increase. <ref name="Koch"> {{Pubmed|12648898|Koch HJ et al. Clinically relevant reduction of lamotrigine concentrations by carbamazepine. J Clin Psychiatry 2005;66:400-1}}</ref>

* Carbamazepine likely speeds the metabolism of lamotrigine, but the clinical significance is unclear.<ref name="freeman">{{Pubmed|9433333|Freeman et al. Mood stabilizer Combinations: A Review of Safety and Efficacy. Am J Psychiatry 1998;155:12-21}}</ref><ref name="levyrh"> Levy RH et al, Metabolic Drug Interactions, Lippincott Williams & Wilkins, Philadelphia, 2000.</ref>

* Lamotrigine may increase blood levels of carbamazepine metabolites, which can result in neurotoxicity (data about this are contradictory). <ref name="freeman" /><ref name="levyrh" />

* These two agents have less significant pharmacologic interactions than do lamotrigine and valproate <ref name="freeman"/><ref name="levyrh"> Levy RH et al, Metabolic Drug Interactions, Lippincott Williams & Wilkins, Philadelphia, 2000.</ref>