Table 1.

Search Criteria for Each Database

Database	Search Strategy	No. of Results Retrieved
PubMed	Original search: February 2021 ((adolesc* OR teen* OR youth* OR “young adult*” OR “young people*” OR “young person*” OR college* OR “high school*” OR “secondary school*” OR “emerging adult*”) AND (alcohol OR drink* OR ethanol) AND (marijuana OR cannabi* OR THC) AND ((cross-fad* OR crossfad*) OR (simultaneous* OR concurr* OR cooccur* OR co-occur* OR co-use*))) AND ((humans[Filter]) AND (English[Filter]))	705
	May 2021 search (without the “humans” limit)	4
	August 2021 search (without the “humans” limit)	53
PsycINFO	Original search: February 2021 (cross-fad* OR crossfad* OR simultaneous OR concurr* OR cooccur* OR co-occur* OR co-use*) (alcohol OR drinking OR ethanol) AND (marijuana OR cannabi* OR THC) (adolesc* OR teen* OR youth* OR young adult* OR young people* OR college* OR high school* OR secondary school* OR emerging adult*)	700
	Limits: Human, English, all journals
	August 2021 search	49
Web of Science	Original search: February 2021 TS = (cross-fad* OR crossfad* OR simultaneous OR concurr* OR cooccur* OR co-occur* OR co-use) TS = (alcohol OR drinking OR ethanol) AND ALL = (marijuana OR cannabi* OR THC) TS = (adolesc* OR teen* OR youth* OR young adult* OR young people* OR young person* OR college* OR high school* OR secondary school* OR emerging adult*)	706
	Limits: English
	August 2021 search	54

Note: THC, delta-9-tetrahydrocannabinol; TS, topic search.