False-positive methadone results with diphenhydramine[15] and doxylamine[16] also have been reported. Daily doses of 100–200 mg of diphenhydramine resulted in false-positive UDS results for three patients.[15] The urine drug concentration needed to show a positive result was 10 mg/L. Doxylamine intoxication resulted in false-positive results for both methadone and opiates when urine samples were checked using EMIT d.a.u (methadone) and EMIT st (opiates) on admission.[16] Opiates were not detected with Abuscreen radioimmunoassay (Roche Diagnostic Systems, Inc., Montclair, NJ) testing. The urine drug concentrations reported were 50 mg/L (for methadone) and 800 mg/L (for opiates).