A new study published today in the scientific journal Addiction has found that opioid smoking appears to be associated with lower mortality risk compared with opioid injecting. The authors, however, caution that opioid smoking still carries a substantial overdose risk and that these results should not be interpreted as suggesting that opioid smoking is safe.
The study analysed substance use treatment data from 2006 to 2021, comparing 287,481 individuals who reported smoking opioids as their primary form of substance use and an equal weighted number of individuals who reported injecting opioids as their primary form of substance use. The outcome of interest was death during treatment, within one year of treatment admission.
The analysis found a mortality rate of 6.5 per 1000 person-years in the smoking cohort and 9.7 in the injection cohort. The mortality rate ratio was 0.67, meaning people who primarily smoked opioids died at two-thirds of the rate of people who primarily injected opioids.
Although smoking rather than injecting opioids may mitigate some risks, smoking opioids still carries a significant risk of death. Smoking recently surpassed injection as the most common route of administration identified among opioid-related fatal overdoses in the United States1, likely driven in part by the rising popularity of opioid smoking and the decrease in opioid injecting.2
Lead author Dr. George Karandinos, a clinical and research fellow at Massachusetts General Hospital and Harvard Medical School, comments: "Smoking opioids instead of injecting likely reduces injection-associated complications like the transmission of HIV and hepatitis C and other serious infections. Our study suggests that smoking also appears to be associated with a lower risk of death. Overestimating the safety of smoking, however, could encourage people to lower their vigilance against overdose, eliminating or reversing any potential risk reduction. People who use opioids and those caring for them must understand that while smoking may reduce harm relative to injection, opioid smoking is not safe. People who smoke opioids should still seek treatment, carry naloxone, avoid using opioids while alone, and avoid sharing smoking equipment, which can lead to inadvertent fentanyl resin exposure and overdose."
Senior author Dr. Daniel Ciccarone adds: "Smoking opioids can be done to deliver a large and rapid dose, as would occur with injection use, and those specific ways of smoking have significant risk for overdose."3
1Tanz LJ. Routes of drug use among drug overdose deaths — United States, 2020–2022. In: Morbidity and Mortality Weekly Report [internet]; 2024 [cited 2024 Feb 15];73. Available from: https://www.cdc.gov/mmwr/volumes/73/wr/mm7306a2.htm
2Karandinos G, Unick J, Ondocsin J, Holm N, Mars S, Montero F, et al. Decrease in injection and rise in smoking and snorting of heroin and synthetic opioids, 2000–2021. Drug and Alcohol Dependence. 2024 Oct 1;263:111419.
3Ciccarone D, Holm N, Ondocsin J, Schlosser A, Fessel J, Cowan A, Mars SG. Innovation and adaptation: The rise of a fentanyl smoking culture in San Francisco. PLoS One. 2024 May 22;19(5):e0303403. doi: 10.1371/journal.pone.0303403.
