Introduction: Criminal offenders have high incidences of injury- and substance-related emergency department visits. Very few studies focus on drug crime offenders or the medical specialties involved in treating these offenders. We aimed to study how drug crime offenders’ treatment events in specialized health care due to injuries, poisonings, or other external causes of morbidity differed from treatment of non-criminal controls and which of the medical specialties were involved in their care. Methods: The study population included 508 former adolescent psychiatric inpatients (age 13–17 years), who were followed up through Finnish national registers. A total of 60 had committed a drug crime during the 10–15 years’ follow-up. They were matched with 120 non-criminal controls from the study population. Hazard ratios (HRs) with 95% confidence intervals (Cl) for drug crime offending were assessed using a Cox regression model. Results: Almost 90% of drug crime offenders had treatment events in specialized health care due to injuries, poisonings, and other external causes of morbidity, compared to 50% of non-criminals. The majority of the drug crime offenders had been treated for accidental injuries (65% vs. 29%; p < 0.001) in comparison to non-criminal controls. More drug crime offenders had been treated for intentional poisonings (42% vs. 11%; p < 0.001) than non-criminal controls. For drug crime offenders, the lifetime probability of a treatment event due to poisoning was almost doubled (HR: 1.89, 95% CI: 1.26–2.84; p = 0.002), and for treatments due to injury, there was a 2.5-fold increase (HR: 2.54, 95% CI: 1.69–3.82; p < 0.001) in comparison to non-criminal controls. Conclusion: In emergency care, substance use screening and referral for appropriate psychiatric and substance abuse treatment services should be considered for all adolescents and young adults attending hospitals due to injuries or poisonings.