Substance abuse has been present throughout human history, as people have used various substances for various purposes, including religious, medicinal, and recreational. The use of certain substances, such as alcohol, has been documented as far back as ancient civilizations, while others, such as opioids and stimulants, were initially used for medicinal purposes before becoming subject to abuse. It is difficult to pinpoint exactly when substance abuse became a problem, as this varies depending on the substance and cultural and historical factors.