Smoking tobacco along with marijuana increases symptoms of cannabis dependence.

Aim: User practices/rituals that involve concurrent use of tobacco and marijuana - smoking blunts and "chasing" marijuana with tobacco - are hypothesized to increase cannabis dependence symptoms.

Design: Ethnographers administered group surveys to a diverse, purposive sample of marijuana users who appeared to be 17-35 years old.

Setting: New York City, including non-impoverished areas of Manhattan, the transitional area of East Village/Lower East Side, low-income areas of northern Manhattan and South Bronx, and diverse areas of Brooklyn and Queens.

Participants: 481 marijuana users ages 14-35, 57% male, 43% female; 27% White, 30% Black, 19% Latino, 5% Asian, 20% of other/multiple race.

Measurements: Among many other topics, group surveys measured cannabis dependence symptoms; frequencies of chasing, blunt smoking, joint/pipe smoking, using marijuana while alone, and general tobacco use; and demographic factors.

Findings: Blunt smoking and chasing marijuana with tobacco were each uniquely associated with five of the seven cannabis dependence symptoms. Across symptoms, predicted odds were 2.4-4.1 times greater for participants who smoked blunts on all 30 of the past 30 days than for participants who did not smoke blunts in the past 30 days. Significant increases in odds over the whole range of the five-point chasing frequency measure (from never to always) ranged from 3.4 times to 5.1 times.

Conclusions: Using tobacco with marijuana - smoking blunts and "chasing" marijuana with tobacco - contributes to cannabis dependence symptoms. Treatment for cannabis dependence may be more effective it addresses the issue of concurrent tobacco use.