Cola (Kola) is a drug, example:
Prevalence and associated risk factors of Kola nut chewing among secondary school students in Osogbo, Nigeria
"Introduction"
"There is sustained global interest in epidemiological studies of substance use among secondary school pupils for various reasons."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4253356/
Any substance that we use for pleasure can be an addiction—this includes sugar. Research shows that our brains are hardwired for pleasure, and sugar works much like many addictive drugs in that it affects the brain's limbic system, the part of the brain that's associated with emotional control.