“…Collectively, these changes may produce a risk environment, especially for overdose, as has been witnessed in various parts of North America ( AMA, 2020 , British Columbia Coroners Service, 2020 , Slavova et al, 2020 ). Fentanyl ( Ciccarone, 2019 , Gomes et al, 2018 ), alcohol ( Tori, Larochelle, & Naimi, 2020 ) and benzodiazepines ( Dasgupta et al, 2016 , Macleod et al, 2019 , McCowan et al, 2009 , Park et al, 2015 ) increase the risk of overdose, particularly when used in combination. The concurrent use of opioids with alcohol and/or benzodiazepines might be particularly problematic in settings where a decreased availability of heroin may lead to reduced tolerance after periods of abstinence, increasing the potential for overdose risk ( Merrall et al, 2010 , Stowe et al, 2020 ).…”