[3] There is some evidence to support its effectiveness in reducing seizure frequency when used as an add-on therapy for drug-resistant focal epilepsy but there are concerns over tolerability.

The most common include dizziness, blurred or double vision, nystagmus, ataxia, fatigue, headaches, nausea, vomiting, sleepiness, difficulty in concentration, and mental sluggishness.

[16] Other, rare, side effects of oxcarbazepine include severe low blood sodium (hyponatremia), anaphylaxis / angioedema, hypersensitivity (especially if experienced with carbamazepine), toxic epidermal necrolysis, Stevens–Johnson syndrome, and thoughts of suicide.

Other side effects include stomach pain, tremor, rash, diarrhea, constipation, decreased appetite, and dry mouth.

Several alternative medications with similar efficacy profiles provide significantly more robust data to support safety during pregnancy.

[citation needed] Oxcarbazepine and licarbazepine are potent inhibitors of CYP2C19 and thus have the potential to increase plasma concentration of drugs, which are metabolized through this pathway.

[3] Other antiepileptics, which are CYP2C19 substrates and thus may be metabolised at a reduced rate when combined with oxcarbazepine, include diazepam,[23][24] hexobarbital,[23] mephenytoin,[23][24] methylphenobarbital,[23] nordazepam,[24] phenobarbital,[23] phenytoin,[24] and primidone.

[23] In addition, oxcarbazepine and licarbazepine are CYP3A4 and CYP3A5 inducers and thus have the potential to decrease the plasma concentration of CYP3A4 and CYP3A5 substrates,[3] including calcium channel antagonists against high blood pressure and oral contraceptives.

[3][25] Oxcarbazepine and MHD exert their action by blocking voltage-sensitive sodium channels, thus leading to the stabilization of hyper-excited neural membranes, suppression of repetitive neuronal firing and diminishment propagation of synaptic impulses.

[3] There was no observable tolerance during a four weeks course of treatment with daily administration of oxcarbazepine or licarbazepine in electroshock test on mice and rats.

[3] Aside from its reduction in side effects, it is presumed to have the same main mechanism as carbamazepine, sodium channel inhibition, and is generally used to treat the same conditions.

[3] People of Asian descent are more likely to carry this genetic variant, especially some Malaysian populations, Koreans (2%), Han Chinese (2–12%), Indians (6%), Thai (8%), and Philippines (15%).

This difference helps reduce the impact on the liver of metabolizing the drug, and also prevents the serious forms of anemia or agranulocytosis occasionally associated with carbamazepine.

[5] In September 2010, Novartis, of which Geigy are part of its corporate roots, pleaded guilty to marketing Trileptal for the unapproved uses of neuropathic pain and bipolar disorder.

[28] Research has investigated the use of oxcarbazepine as a mood stabilizer in bipolar disorder, with further evidence needed to fully assess its suitability.