Symptoms of substance use disorder vary widely from person to person and may include physical, psychological, or behavioral signs.

If you feel as if you or someone close is frequently using a substance like alcohol, tobacco, or opioids in a way that affects you or others negatively, you may be worried that you (or they) have developed a substance use disorder (SUD).

SUD is a complex and challenging condition that affects nearly 21 million people in the United States. That’s more than the number of people with any cancer combined.

While misconceptions surrounding substance use may lead you to believe that the condition is caused by a person’s behavior or lack of willpower, it’s important to keep in mind that that’s untrue. Biological factors beyond a person’s control play a major role.

Activation of the brain’s reward center is the primary reason for most addictions. Whether the SUD is due to alcohol, stimulants, or opioids, the rewarding feeling gained from use — involving an abnormally high dopamine release — is often overpowering.

Continued use of the substance may lead to changes in the brain’s structure and function. This can result in intense cravings, withdrawal symptoms, learning and memory problems, and personality changes.

Learning to recognize the signs and symptoms of substance use disorder can be the first step toward seeking help and receiving treatment.

Substances for which an individual can form a substance use disorder include:

  • alcohol
  • cannabis
  • hallucinogens, including LSD and phencyclidine
  • inhalants
  • opioids, such as heroin or prescription medications
  • sedatives, hypnotics (sleep-inducing medications), or anxiolytics (anti-anxiety medications)
  • stimulants like amphetamines or cocaine
  • tobacco

Dependence on two or more substances is common. For example, evidence suggests that among people with heroin use disorder:

  • over 66% are also dependent on nicotine
  • nearly 25% have alcohol use disorder
  • over 20% have cocaine use disorder

Similarly, among those with cocaine use disorder:

  • nearly 60% have alcohol use disorder
  • about 48% are dependent on nicotine
  • over 21% have cannabis use disorder

Signs and symptoms of substance use vary widely from person to person and depend on the substance, length and severity of use, and an individual’s personality. Below are some of the general symptoms of substance use.

Physical signs of substance use disorder

  • sudden weight loss or gain
  • pupils that are smaller or larger than usual
  • bloodshot eyes
  • changes in appetite and sleeping patterns
  • slurred speech
  • impaired coordination or tremors
  • deterioration of physical appearance or changes in grooming practices
  • runny nose
  • unusual odors on breath, body, or clothes

Psychological signs of substance use disorder

  • feeling paranoid, anxious, or fearful
  • unexplained change in personality
  • feeling “spaced out”
  • lack of motivation
  • feeling excessively tired
  • periods of excessive energy, mental instability, or restlessness
  • sudden changes in mood
  • increased agitation or anger

Behavioral signs of substance use disorder

  • beginning to act in a secretive or suspicious way
  • experiencing problems in relationships due to the condition
  • using more than originally intended (being unable to control the substance use)
  • neglecting family and friendships, as well as duties at home, school, or work
  • getting into legal trouble, including driving under the influence, fights, or accidents
  • suddenly changing hobbies, friends, or activities
  • using the substance under conditions that may not be safe, such as sex without a condom or other barrier method, driving under the influence, or using syringes that are not sterile
  • experiencing sudden unexplained financial problems, which may include frequently asking for money or stealing
  • frequently trying to avoid or relieve withdrawal symptoms
  • experiencing increased tolerance for the substance, which may cause the person to use more and more of it
  • noticing that life revolves around substance use and recovering from use, e.g., always thinking about using or consumed with how to get more
  • no longer engaging in previously enjoyed activities due to substance use
  • continuing to use despite negative health consequences

To assess a person’s risk for SUD, a healthcare professional may begin with a short screening. This may then be followed by a comprehensive evaluation and a referral to a licensed alcohol and drug counselor, psychologist, or psychiatrist.

One commonly used short screening for substance use is the UNCOPE questionnaire.

Although it was originally developed based on the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-4), research shows that it may also help identify SUD based on the fifth edition (DSM-5).

The UNCOPE screening asks the following questions:

  • Have you continued to use alcohol or drugs longer than you originally planned?
  • Have you ever neglected some of your usual responsibilities because of your substance use?
  • Have you ever wanted to cut back or quit using the substance but could not?
  • Has a loved one or anyone else ever told you they objected to your alcohol or drug use?
  • Have you ever found yourself preoccupied with the thought of using alcohol or drugs?
  • Have you ever used alcohol or drugs to soothe emotional pain, such as sadness, anger, or boredom?

For a more comprehensive evaluation and to diagnose substance use disorder, most clinicians rely on the following 11 criteria published in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5):

  • feeling as if you have to consume the substance regularly (daily or several times a day) and more than originally planned
  • spending a large portion of your time finding, using, and/or recovering from the substance
  • craving the substance
  • needing more of the substance to get the same effect
  • experiencing withdrawal when you stop taking the substance
  • being unable to meet obligations at home, work, or school because of using the substance
  • recurring thoughts of quitting but not managing to quit successfully
  • continuing to use despite the problems it causes in relationships
  • continuing to use despite mental or physical health problems caused or worsened by it
  • giving up or cutting back on social or recreational activities due to the substance use
  • using the substance under situations that may be unsafe, such as driving under the influence or using syringes that are not sterile

A substance use disorder can be considered mild, moderate, or severe based on the number of symptoms a person exhibits within a 12-month period.

According to the DSM-5, a person must have the following number of symptoms outlined above to be diagnosed with mild, moderate, or severe SUD:

  • Mild: 2–3 symptoms
  • Moderate: 4–5 symptoms
  • Severe: 6 or more symptoms

Dual diagnosis

Diagnosis is also more complex for people with both a substance use disorder and a mental health condition — known as a dual diagnosis. That’s because it’s often difficult to disentangle overlapping symptoms, such as withdrawal and mental illness symptoms.

In 2019, 9.5 million adults in the United States lived with both mental illness and a substance use disorder, according to the National Survey on Drug Use and Health.

People with a dual diagnosis often have symptoms that are more severe, persistent, and resistant to treatment than those with an SUD alone.

Signs and symptoms of substance use disorder vary from person to person. The most noticeable signs include:

  • disinterest in school, work, or other activities
  • physical health issues like bloodshot eyes, lack of energy, or weight loss or gain
  • lack of interest in grooming or keeping clean
  • behavioral changes like acting in a secretive manner, increased irritability or changes in mood, or being fearful or paranoid
  • financial problems

Recognizing these signs and symptoms may be the first step toward recovery.

If you suspect that you or someone you love has a substance use disorder, consider reaching out to a trusted healthcare professional for an evaluation. Together, you can develop the right treatment plan for you.

If you’re not quite ready to see a healthcare professional yet or you’re looking for more information, maybe check out the organizations below, which offer additional resources and support groups: