If someone has overdosed and has serious symptoms such as passing out or trouble breathing, give them naloxone if available, then call 911. If the person is awake and has no symptoms, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: slow/shallow breathing, nausea, vomiting, loss of appetite, sweating, stomach/abdominal pain, slow heartbeat, extreme tiredness, yellowing eyes/skin, dark urine, coma.