Will Lamotrigine Make Me Fail A Drug Test?

Will Lamotrigine Make Me Fail A Drug Test? Lamotrigine has the potential to provide a false-positive result for PCP on the Bio-Rad TOX/See rapid urine toxicology screen. How long is lamotrigine detectable in urine? Official Answer. Lamotrigine will be out of your system after your last dose in about 338.8 hours (approximately 14 days). After