an opioid addiction. Also, in 2018, after being prescribed an opioid medication, about 10.3 million people ended up misusing it, and 47,600 people died from an overdose. Causes The Centers for Disease Control and Prevention describe the U.S. opioid epidemic as having arrived in three waves. The first wave, which marked the start of the epidemic, began in the 1990s due to the push towards using opioid medications for chronic pain management and the increased promotion by pharmaceutical companies for medical professionals to use their opioid medications. During this time, around 100 million people in the United States were estimated to be affected by chronic pain; however, opioids were only reserved for acute pain experienced secondary to cancer or terminal illnesses. Physicians avoided prescribing opioids for other medical conditions because of the lack of evidence supporting their use, the concern of opioids having addictive properties, and the fear of being investigated or disciplined for liberal opioid practices. However, in 1980, a letter to the editor featured in the New England Journal of Medicine (NEJM) challenged these notions. The letter advocated for more liberal use of opioids in pain management, which the World Health Organization eventually supported. In addition, medical organizations began to push for more attentive physician responses to pain, referring to pain as the "fifth vital sign." This was coupled with the promotion of opioids by pharmaceutical companies who insisted that patients could not become addicted. Opioids became an acceptable treatment for a wide variety of conditions, leading to a consistent increase in opioid prescriptions. From 1990 to 1999, the total number of opioid prescriptions grew from 76 million to approximately 116 million, which led to them becoming the most prescribed class of medications in the United States. Mirroring the positive trend in the volume of opioid pain relievers prescribed is an increase in the admissions for substance use disorder treatments and an increase in opioid-related deaths. This illustrates how legitimate clinical prescriptions of pain relievers are being diverted through an illegitimate market, leading to misuse, addiction, and death. With the increase in volume, the potency of opioids also increased. By 2002, one in six drug users was prescribed drugs more powerful than morphine; by 2012, the ratio had doubled to one in three. The most commonly prescribed opioids have been oxycodone and hydrocodone. The second wave of the opioid epidemic started around 2010 and is characterized by the