Withdrawal is not a disease, but rather a syndrome. Medically speaking, there is an important difference because a disease refers to an established condition, whereas a syndrome refers to a set of symptoms. Withdrawal is classed as a syndrome because it refers to the symptoms a person experiences when they suddenly stop taking a substance that their body is physically dependent on. In the case of opioids, you can think of withdrawal as a symptom and an Opioid use disorder (OUD) as the established condition. OUD is the clinical term that is used when someone has become physically dependent on one or more opioid substances and uses them despite experiencing a negative impact on their quality of life.
So, it’s more useful to think of addiction as the disease, and withdrawal as the symptoms that happen when someone tries to stop taking the substance they are addicted to. It’s important to remember that withdrawal is a medical issue that can be very challenging for the person going through it. Symptoms are very real and can cause intense physical and psychological discomfort.