Substance Use Disorder 

Substance use disorder occurs when a person's use of alcohol or another substance (drug) leads to health issues or problems at work, school, or home. Substance use may lead to a fatal overdose. The exact cause is not known.  A person’s genes, the action of the drug, peer pressure, emotional distress, and environmental stress can all be factors. 1 

Dual Diagnosis (also known as co-occurring disorders)

Dual Diagnosis is a term for when someone experiences a mental illness and a substance abuse problem simultaneously.  Dual Diagnosis is a very broad category. It can range from someone developing mild depression because of binge drinking, to someone's symptoms of bipolar disorder becoming more severe when that person abuses heroin during periods of mania.  

Either disorder (substance abuse or mental illness) can develop first.  A person experiencing a mental health condition may turn to drugs and alcohol as a form of self-medication to improve the troubling mental health symptoms they experience. 2



Tolerance happens when a person no longer responds to a drug in the way they did at first. So it takes a higher dose of the drug to achieve the same effect as when the person first used it. This is why people with substance use disorders use more and more of a drug to get the “high” they seek. 3



Dependence means that when a person stops using a drug, their body goes through withdrawal. Many people who take a prescription medicine every day over a long period of time can become dependent; when they go off the drug, they need to do it gradually, to avoid withdrawal discomfort. But people who are dependent on a drug or medicine aren’t necessarily addicted. 3


Unlike tolerance and dependence, addiction is a disease;; but like tolerance and dependence, addiction can result from taking drugs or alcohol repeatedly. If a person keeps using a drug and can’t stop, despite negative consequences from using the drug, they have an addiction (also called a severe substance use disorder). But again, a person can be dependent on a drug, or have a high tolerance to it, without being addicted to it. 3


Additional Information:





About Substances

To learn more about various substances, how they are commonly used, and their effects on the human body, see the list below:

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NM CAN thanks Western CT Coalition for it's support.

The Department of Mental Health & Addiction Services partially funds this program.