Do medications that difficult children take for bipolar, etc. have any effect on drug testing? difficult child has had drug testing done about 5 times in the ER and pysch hospital. They all came up negative for marijuana. He admitted the other day that both times that he was in the ER & sent to the hospital, he had smoked pot. He said that he couldn't believe when they said that the testing came back negative. Naturally he had denied any drug use at the time of testing and the whole time in the hospital.