Measuring the temporal association between cannabis and tobacco use among Co-using young adults using ecological momentary assessment.

•The link between cannabis and tobacco use by young adults is not well understood.•28-day ecological momentary assessment (EMA) was used to track co-users.•Cannabis and tobacco use were significantly temporally associated among co-users.•There was considerable variability in the temporal association across participants.•Heavier cannabis users were more likely to use cannabis and tobacco concurrently.