According to the DSM-5, 11 different criteria signal that a SUD may be present. Whether a SUD is classified as mild, moderate or severe is determined by how many of the following criteria are met:

1. Taking the substance in larger amounts or for longer than was intended. For example, intending to take one prescription opioid pain reliever, but taking three instead.
2. Wanting to cut down or stop using the substance but not managing to do so.
3. Spending a lot of time getting, using, or recovering from use of the substance. For example, someone may spend time “doctor shopping,” or visiting multiple physicians to obtain multiple prescription medications.
4. Cravings and urges to use the substance. 
5. Not managing to do what you should at work, home or school, because of substance use.
6. Continuing to use, even when it causes problems in relationships. For example, arguments with family members, significant others, or friends.
7. Giving up important social, occupational or recreational activities because of substance use.
8. Using substances again and again, even when it puts you in danger.
9. Continuing to use, even while knowing you have a physical or psychological problem that could have been caused or made worse by the substance, for example, depression or anxiety.
10. Needing more of the substance to get the effect you want, called tolerance.
11. Development of withdrawal symptoms, which differ by the substance used, and can include shaking, sweating, and nausea.  These symptoms can be relieved by taking more of the substance.