Cannabis can be smoked by itself (e.g. marijuana cigarettes, or in bongs or pipes) or can be rolled with small amounts of tobacco to facilitate smoking (referred to as mulling in some countries) (20;76;77). Some studies contend that these small amounts of tobacco produce nicotine withdrawal which cannabis users stave off by sustained use of tobacco-containing cannabis preparations (78;79). Preliminary research also indicates that cannabis and tobacco are often smoked on the same occasion and that these simultaneous users are at greater risk for cannabis use disorders (80). Similar increases in cannabis involvement have been noted in those who report chasing cannabis with tobacco smoking (i.e., closely following cannabis smoking with tobacco) (81). In both those co-administering tobacco and cannabis and those smoking cigarettes and joints on the same occasion, an additional source of respiratory adaption may arise from additives in manufactured tobacco. For instance, in addition to flavorants, cigarettes typically contain compounds (e.g. salicylates) that have anti-inflammatory and anesthetic effects which may facilitate cannabis inhalation (82).
