When a drug is laced, it means another substance has been added to it, sometimes intentionally by a dealer to increase potency or addiction, and sometimes unknowingly passed along through a supply chain where contamination occurred earlier. Marijuana has been found laced with fentanyl, methamphetamine, PCP, cocaine, and other synthetic opioids. The addition is invisible. It has no distinct smell. It leaves no visual trace. Standard home drug tests do not detect it.