More than one in ten adults--and about one in three young adults--report past year cannabis use in Canada. While cannabis use is associated with a variety of health risks, current policy prohibits all use, rather than adopting a public health approach focusing on interventions to address specific risks and harms as do policies for alcohol. The objective of this paper was to develop 'Lower Risk Cannabis Use Guidelines' (LRCUG) based on research evidence on the adverse health effects of cannabis and factors that appear to modify the risk of these harms.Relevant English-language peer-reviewed publications on health harms of cannabis use were reviewed and LRCUG were drafted by the authors on the basis of a consensus process.The review suggested that health harms related to cannabis use increase with intensity of use although the risk curve is not well characterized. These harms are associated with a number of potentially modifiable factors related to: frequency of use; early onset of use; driving after using cannabis; methods and practices of use and substance potency; and characteristics of specific populations. LRCUG recommending ways to reduce risks related to cannabis use on an individual and population level--analogous to 'Low Risk Drinking Guidelines' for alcohol--are presented.Given the prevalence and age distribution of cannabis use in Canada, a public health approach to cannabis use is overdue. LRCUG constitute a potentially valuable tool in facilitating a reduction of health harms from cannabis use on a population level.