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J Psychiatry Neurosci. 2004 Jan;29(1):40-7.

Heroin and cocaine co-use in a group of injection drug users in Montréal.

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Department of Psychology, University of Guelph, Guelph, Ont.



To describe the pattern of co-use of heroin and cocaine in individuals who were not receiving methadone maintenance treatment.


Structured interviews.


Community hospital.


Individuals (n = 1111) selected from a cohort of out-of-treatment injection drug users in Montréal, Que.


Frequency (injections per day) and quantity (number of days of use) of heroin, cocaine and speedball (the simultaneous administration of heroin and cocaine) use reported in the month preceding the interview.


About 50% of the sample reported using only cocaine intravenously (C group), about 8% reported using only heroin (H group) intravenously and about 15% reported using both heroin and cocaine (HC group) intravenously. Reported cocaine consumption was similar in the HC and C groups. Heroin was used on fewer days by the HC than by the H group, but the number of injections per day was similar. Speedball use, which was quantified independently from heroin and cocaine use, was reported almost exclusively by the HC group, and speedball was used less often than either heroin or cocaine alone. Finally, a similar proportion of individuals in the C and the HC groups consumed alcohol in the 24 hours preceding the interview, but a larger proportion of individuals in the HC group reported the use of marijuana.


In a cohort of injection drug users in Montréal, cocaine was the most prevalent illicit drug. Furthermore, about 70% of the heroin users also injected cocaine, but not in the form of speedball. Thus, the sequential co-use of heroin and cocaine is highly prevalent in Montréal and deserves particular clinical attention.

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