While it’s difficult to know if someone is dealing with a substance use disorder just by looking at how they act, there are some signs you can look for.
Some common signs that may be concerning for a substance use disorder are changes in behavior, poor sleep, mood dysregulation, loss of motivation, weight changes, changes in personal hygiene, changes in mood, etc.
Signs Someone May have a Substance Use Disorder
Substance use disorders (SUD) are highly individualized. How one person struggles with drug misuse may look very different from another.
Many of the signs of addiction that will be discussed are not exclusively signs of drug misuse. It’s also possible that symptoms discussed may signal a person is struggling with some combination of physical and mental health issues unrelated to addiction.
With that said, there are a variety of symptoms relatively common among people who struggle with an addiction or substance use disorder. These symptoms can be further broken down into three categories: physical signs, behavioral signs, and psychological signs.
Physical Signs of Addiction
Depending on the severity of a person’s addiction, they will often show signs of deteriorating health and a reduced ability for self-care. Sometimes this is a direct result of their drug use, such as if their drug use is damaging their body or they’re experiencing withdrawal, and other times it may be an indirect result, such as a reduced ability to financially support their needs or make time for good hygiene practices.
Some physical signs of addiction include the following:
- Eye changes, including eyes being bloodshot or pupils being unusually small or large
- Significant weight changes
- Impaired coordination
- Unkempt or dirty appearance or drastic changes in personal hygiene
- Unusual odors
Behavioral Signs of Addiction
SUD almost always involves changes in behavior, often putting a strain on their relationships with friends, family, and colleagues. In some cases, a person can develop significant behavioral problems to the point where it becomes difficult to function at work, school, or at home. These behaviors tend to affect both professional and interpersonal relationships.
Some common behavioral signs of addiction include:
- Abandoning activities or hobbies that were previously enjoyed
- Acting suspicious, secretive, or paranoid
- Getting into frequent legal trouble
- Getting into physical altercations
- Asking for or borrowing money, or stealing
- Withdrawing from friend or family
Psychological Signs of Addiction
SUD often results in changes in mental health. The psychological signs of addiction aren’t always obvious to outside observers, but they can include the following:
- Anxiety, fear, and paranoia
- Difficulty finding motivation or focusing on tasks
- Periods of mania, nervousness, or emotional instability
- Sudden mood swings, including irritability and bursts of anger
- Unexplained changes in personality or attitude
Signs of Use Common to Different Drug Types
Signs of Alcohol Misuse
Alcohol use disorder is one of the more common and destructive SUDs. Alcohol can have a significant impact on a person’s health over time. Alcohol withdrawal can be so severe that it is actually life-threatening if a person doesn’t undergo medical supervision while attempting to discontinue use.
Alcohol withdrawal symptoms can include nausea, mood swings, tremors, sleep problems, and hallucinations or even seizures. Over time, alcohol use can damage a person’s organs, affecting the heart, liver, stomach and pancreas. Alcohol can also affect short and long term memory. 
Signs of Opioid Misuse
Opioid misuse can cause many of the symptoms already discussed that are common to general drug misuse. Opioid use disorder is notably associated with drowsiness and a decreased libido, and people who use opioids often experience significant weight loss with prolonged use. Opioid withdrawal is flu-like and often uncomfortable, which is part of what makes quitting opioids particularly difficult. Significant opioid use can cause dangerous respiratory depression similar to alcohol use. It is especially dangerous if a person combines opioids with other drugs that have a similar effect.
Signs of Stimulant Misuse
Stimulants such as cocaine and amphetamines cause a person to experience a burst of euphoria and energy, sometimes causing them to go for unusually long periods without eating or sleeping. People who use stimulants may seem very energetic and may be unable to sit still or rest. They may talk for long periods of time, only to suddenly stop and “crash,” becoming depressive and lethargic. Stimulants can often cause people to become anxious and irritable, and they can sometimes cause paranoia. Users may show signs of significant weight loss and have issues with dry mouth and nosebleeds. As with other drugs, the signs of stimulant misuse are dependent on the doses regularly taken, with more severe side effects associated with higher doses and long-term use.
It can be extremely stressful to know how to help someone who is experiencing a problem with substance use. The first step may be recognizing the signs of substance misuse. If you have concerns that a friend or loved one may have a substance use disorder, encourage them to reach out to their doctor for professional help.
Medically Reviewed By Elena Hill, MD, MPH
Elena Hill, MD; MPH received her MD and Masters of Public Health degrees at Tufts Medical School and completed her family medicine residency at Boston Medical Center. She is currently an attending physician at Bronxcare Health Systems in the Bronx, NY where ... Read More
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