Background: Recurrent opioid usage despite negative consequences is a hallmark of opioid use disorder. There are about 16 million people with an opioid use disorder worldwide, including over 2.1 million in the United States; annually, opioids cause over 120,000 deaths. When visiting Egypt several epidemiological studies on drug abuse in Egypt were conducted in the past few decades. 5.5% of high school students tested positive for cannabis use, while 0.84% tested positive for opiate use. Objective: Review of literature about opioid use disorder. Methods: We scoured scholarly papers and databases including PubMed, Google Scholar, and Science Direct for information on Opioid Use Disorder (OUD) between July 2013 and September 2022, however, only the latest or most comprehensive study was considered. The authors also assessed the usefulness of references taken from similar books. Documents written in languages other than English have been overlooked because of a lack of funding to translate them. Unpublished articles, oral talks, conference abstracts, and dissertations were all generally agreed upon not to constitute valid scientific investigation. Conclusion: Addiction of opioids is characterized by compulsive opioid seeking and use, impaired self-control regarding drug intake, and the emergence of negative effective symptoms (hyperkatifeia) in the presence of drug absence. The binge/intoxication phase of substance abuse initiates an allostatic chain reaction that results in the subsequent withdrawal/negative affect phase and the preoccupation/anticipation phase. With continued drug use, each stage builds on the previous ones until addiction has set in. Medical intervention is used to treat opioid withdrawal symptoms (OWS). Opioid agonist therapy (OAT) is the gold standard for relieving OWS in individuals with moderate to severe OUD.