Chuck has been struggling this spring with anxiety and nausea. He describes the sickness as “a nightmare.” For days, he stayed home, building back his strength and swallowing tinctures of herbs like skullcap and passionflower as his body withdrew from opioids. He ventured back outside on a sunny Friday afternoon. A 33-year-old Midwesterner with a slight beard, Chuck smokes cigarettes to calm his nerves on his friend’s back patio. A user of heroin and other drugs since his early 20s, Chuck said he’s always been able to get sober when he wanted. But opioids have been harder to kick lately, as the powerful synthetic opioid fentanyl has seeped into drug supplies. “People get sick a lot faster than they would from what used to be out there, from standard heroin or pills and that sort of thing,” Chuck said. “It’s a lot harder for people to stop doing it.” Fentanyl is cheaper and stronger than heroin, so it can be used to bump up the strength of heroin and other drugs. But because there’s no telling the strength of the fentanyl in a doctored drug, it’s also more likely that people could overdose after taking drugs that contain fentanyl.