Why shouldn’t tobacco be consumed with cannabis?

Tobacco is harmful on its own, and the co-use of tobacco and cannabis has been associated with developing a dependence on either substance, negative mental health outcomes, engagement in other risk-taking behaviours, and increased difficulty stopping cannabis use. There is some evidence that suggests combining tobacco with cannabis can lead to smoking initiation as well. In addition, using both substances may also lead to increased health risks compared to using just one or the other, such as the impact on the respiratory system.