My son takes Lamotrigine, Trileptal, Zyprexa, Trzodone, Mellaril, Levoxyl and Ditropan, He has also been taking BC powder for daily headaches, and the generic Mucinex for his allergy symptoms. He was drug tested last night while being assessed for mental health hospitalization and their quick test determined he tested positive for pcp. He has not been out of the house unless we take him to his recovery meetings or church. He isolates when he starts losing his stabilization with his medications. We were told the Lamotrigine could of caused this. Can you give me any guidance or confirmation on why he had a false positive test? Thank you.