Updated on February 6, 2024
9 min read

How to Tell if Someone Is on Drugs

Key Takeaways

Different types of drugs produce different effects on your physical and mental health. They can also impact your behavior. There are common signs and symptoms that suggest a person is on drugs.

Drugs typically refer to highly addictive substances such as cocaine, heroin, and meth. Continued use can lead to drug tolerance, physical dependence, addiction, and substance abuse disorders (SUDs).

Drug abuse leads to unhealthy behaviors that can ruin your life. However, knowing the signs and symptoms of drug use can help you get help before it’s too late.

How to Tell if Someone is Using Stimulant Drugs

Certain prescription stimulants treat attention-deficit hyperactivity disorder (ADHD) and narcolepsy. People who abuse these drugs can easily become addicted or dependent on them.

Some commonly abused stimulants include:

  • Cocaine
  • Meth
  • Amphetamine
  • Crack

Signs and Symptoms of Stimulant Drug Abuse

Stimulants or “uppers” refer to drugs that increase bodily activities. Signs that your loved one may be abusing stimulants include:

  • Heightened attention and alertness
  • Boost in energy
  • Large, dilated pupils
  • Sweating
  • Rapid heartbeat
  • Elevated blood pressure
  • Appears to have excess energy
  • Increased motivation
  • Being jittery and restless
  • Hyperactivity
  • Sudden weight loss
  • Fixating or obsessing over something
  • Flight of ideas and racing thoughts
  • Increased confidence and sense of well-being
  • Insomnia or difficulty sleeping
  • Anxiety or nervousness

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How to Tell if Someone is Using Depressants

Some prescription depressants that are misused include:

  • Benzodiazepines like diazepam (Valium®)
  • Sedatives like zolpidem (Ambien®)
  • Barbiturates like phenobarbital (Luminal®).

Signs and Symptoms of Depressant Drug Abuse

Depressants or “downers” are drugs that slow down brain activity. They often treat muscle spasms, anxiety disorders, and sleep problems.

Signs that your loved one may be abusing depressants include:

  • Dry mouth
  • Decreased blood pressure
  • Slow breathing
  • Poor concentration
  • Slurred speech
  • Confused mental state
  • Lightheadedness or dizziness
  • Headaches
  • Memory problems

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How to Tell if Someone is Using Opioids

Opioids are often used to treat chronic pain.

Commonly abused opioids include:

  • Oxycodone (OxyContin®)
  • Hydrocodone (Vicodin®)
  • Fentanyl
  • Heroin

Signs and Symptoms of Opioid Drug Abuse

Opioids enhance feelings of pleasure. They create a short-lasting, strong sense of well-being.

Your loved one may be misusing opioids if they exhibit the following:

  • Slow or shallow breathing
  • Slurred speech
  • Shaking
  • Nausea or vomiting
  • Sweating
  • Drowsiness
  • Weight loss
  • Changes in sleeping pattern
  • Decreased libido
  • Loss of coordination

How to Tell if Someone is Using Hallucinogens

Hallucinogens are diverse drugs that can alter your awareness and perception. They can distort your surroundings, thoughts, and feelings.

Some hallucinogens include:

  • Lysergic acid diethylamide (LSD)
  • Dimethyltryptamine (DMT)
  • Ketamine,
  • Dextromethorphan (DM), an ingredient of over-the-counter (OTC) drugs used to treat coughs and colds, are hallucinogens sold in the black market.

Signs and Symptoms of Hallucinogen Drug Abuse

Signs that a loved one is using hallucinogens may include:

  • Numbness
  • Elevated temperature and blood pressure
  • Increased breathing and heart rate
  • Appearing disoriented or confused
  • Nausea and vomiting
  • Dizziness
  • Hallucinations
  • Memory loss
  • Feeling detached from oneself and the environment
  • Psychological distress (e.g., panic, paranoia, fear, anxiety)
  • Feelings of invulnerability and increased strength
  • Aggression

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Physical Signs of Drug Use

Signs of drug use can show in a person's appearance and how they take care of themselves. Common physical symptoms of drug use include:

  • Poor hygiene 
  • Red, bloodshot eyes
  • Larger or smaller pupils than usual
  • Poor skin tone
  • Appearing tired or run down
  • Poor physical coordination
  • Slurred speech
  • Unusual odor on breath, body, or clothes
  • Weight loss or weight gain
  • Overall deterioration in physical appearance

How a person uses drugs can also leave visible marks or change their appearance. Drugs that are snorted or administered intravenously may leave various physical signs.

How to Tell if Someone is Snorting Drugs

Drugs like cocaine, heroin, and crystal meth are available in powder form. Some drug users snort or “huff” them directly up the nose.

Physical symptoms of drug snorting include:

  • Runny or stuffy nose that doesn’t get better
  • Frequent nose bleeding
  • Unusual nasal discharges
  • Recurring nasal infections (e.g., sinusitis)

How to Tell if Someone is Shooting Up Drugs

Heroin, crystal meth, and other drugs can also be administered intravenously. This means the drugs are injected directly into the bloodstream.

People who inject drugs will have track marks on major veins. Track marks can appear as puncture wounds, scabs, or bruises on the forearms, hands, legs, and feet.

Other signs and symptoms that someone is shooting up drugs include:

  • Skin infections on needle insertion sites
  • Wearing long-sleeved shirts or pants to cover track marks

Behavioral Signs of Drug Use

Drug use alters certain parts of the brain. This can lead to personality and behavioral changes. These changes tend to be sudden.

You might be able to observe sudden changes in people you know well, such as a family member. This is especially true if you're familiar with their normal behavior. 

The most common behavioral signs of drug abuse include:

  • Low motivation
  • Loss of interest in activities they used to enjoy
  • Decline in work or school performance
  • Frequent work or school absences
  • Seeming withdrawn or inactive
  • Lying and engaging in secretive behavior
  • Changes in sleeping patterns
  • Changes in eating habits or appetite loss
  • Drastic changes in relationships
  • Issues with financial management or spending more money than usual
  • Defensive when asked about substance use
  • Inability to explain reasons for doing something
  • Getting into frequent accidents or injuries
  • Engaging in risky sexual behavior

Psychological Signs of Drug Use 

Illicit drugs are known for their psychoactive properties or ability to alter brain function. When you misuse these drugs, you'll experience changes in mood, level of awareness, thoughts, and feelings. 

The psychoactive nature of drugs also causes behavioral changes. Some of these are more devastating than others.6

Common psychological signs include:

  • A negative change in personality or attitude
  • Depression and anxiety
  • Irritability and mood swings
  • Low self-esteem
  • Paranoia
  • Hallucinations
  • Difficulty with cognition or thinking
  • Memory loss

Effects & Risks of Commonly Abused Drugs

Heroin, methamphetamine, and cocaine are three of the most commonly abused drugs in the U.S.4 Below are some signs of possible drug use, along with their side effects and complications.


Heroin is an illegal, highly addictive opioid drug. It is made from morphine, which comes from poppy plants. This drug looks like a white or brown powder or sometimes a black sticky substance.

Heroin can be injected, sniffed, snorted, or smoked. As many as 745,000 Americans suffer from Heroin drug abuse.4 Heroin is a depressant that slows down certain functions in the brain and nervous system.

Signs of Heroin Abuse

Signs that your loved one may be using heroin include:

  • Pinpoint pupils
  • Sleepiness
  • Slow movement
  • Track marks” or needle marks on arms
  • Severe itching
  • “Nodding” or going in and out of consciousness
  • Withdrawal symptoms including insomnia, sweating, nausea, and goosebumps

Side Effects of Heroin Abuse

Side effects of heroin abuse include:

  • Warm flushing of the skin
  • Dry mouth
  • Heavy feeling in extremities 
  • Short-lived state of euphoria followed by drowsiness
  • Slowed heart rate, breathing, movement, and brain activity
  • Decreased appetite, thirst, reflexes, and sexual desire

Heroin can also cause long-term health complications such as:

  • Damage to the lungs, liver, kidneys, or brain
  • Contracting Hepatitis or HIV
  • Blood poisoning
  • Convulsions
  • Coma
  • Death

Meth (Methamphetamine)

Methamphetamine (meth) is an illegal, highly addictive stimulant drug. Meth appears as a white, odorless powder that easily dissolves in water or alcohol. It affects about 2 million Americans.4

Meth has one of the highest global rates of misuse. Over 14 million people (5.4 percent of the population) have tried meth at least once.

Methamphetamine is very similar to amphetamines, or, prescription drugs used to treat medical conditions like ADHD. However, the side effects of taking meth last longer and are often more toxic. 

Signs of Meth Use

Signs that your loved one may be using meth include:

  • Excessive itching or scratching
  • Skin sores on arms and face
  • Burns on lips or fingers
  • Nervousness, restlessness, or inability to sit still
  • Rotten teeth or gums
  • Appearing sick or ill
  • Twitching, jerking movements (loss of motor skill)
  • Paranoia
  • Aggression or violence
  • Excessive sweating even in cold temperatures
  • Rapid, irrational, and slurred speech
  • Teeth grinding
  • Runny or bloody nose
  • Sudden weight loss
  • Poor personal hygiene 
  • Extreme or bizarre behavior

Side Effects of Methamphetamine Abuse

Common side effects of meth abuse include:

  • Rapid heart rate
  • Irregular heart rate
  • Increased blood pressure
  • Hyperthermia (elevated body temperature)

Methamphetamine abuse also causes long-term health complications such as:

  • Depression
  • Permanent psychological problems
  • Brain damage
  • Liver damage
  • Fatal lung and kidney disorders
  • Stroke or heart problems
  • Death


Cocaine is an illegal, highly addictive stimulant drug made from the coca plant. Cocaine appears as a fine, white powder.

Cocaine can be snorted or rubbed into the gums. It may also be injected into the bloodstream. It is abused by over 5.5 million people in the U.S.4

Signs of Cocaine Use

Signs that your loved one may be using cocaine include:

  • Increased talkativeness
  • Hypersensitivity to light, sound, and touch
  • Dilated pupils
  • Mood swings
  • Overconfidence
  • Overexcitement
  • Frequent nosebleeds
  • Ability to perform physical and intellectual tasks quickly or more slowly than usual 

Side Effects of Cocaine Abuse

Side effects of cocaine abuse include:

  • Brief but intense feelings of euphoria
  • Stimulation of the central nervous system (CNS)
  • Constricted blood vessels
  • Tremors
  • Vertigo
  • Muscle twitches
  • Increase in pulse, body temperature, blood pressure, and respiratory rate
  • Extreme excitability or anxiety
  • Sleeplessness and chronic fatigue

Abusing cocaine also causes long-term health complications, including:

  • Bleeding and damage to nasal passages
  • Paranoid psychosis, hallucinations, and mental abnormalities
  • Impaired driving ability
  • Abdominal pain and nausea
  • Malnourishment
  • Cardiac arrest
  • Seizures
  • Parkinson’s disease
  • Death caused by heart or respiratory failure

When to Seek Help?

If you think your loved one is abusing drugs, it's important to get help early. By having an early intervention, you can improve their chances of a successful recovery.

Consider seeking help from medical professionals and addiction specialists. They can give you advice on rehab facilities, treatment options, and resources to help you and your loved one.

Remember to offer help and support, especially if they're interested in getting treatment. Encourage them by helping them explore other treatment methods and ways to get sober.

Drug Addiction Treatment Options

Many treatment options are available for drug addiction. Not everyone responds to treatment the same way so it's important to find the right treatment program for you or your loved one.

Different types of treatment options include:

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Updated on February 6, 2024
6 sources cited
Updated on February 6, 2024
  1. Monitoring the Future Study: Trends in Prevalence of Various Drugs.” National Institute on Drug Abuse.

  2. Global Burden of Disease Study 2017.” Institute for Health Metrics and Evaluation.

  3. QuickStats: Number of Emergency Department Visits*,† for Substance Abuse or Dependence§ per 10,000 Persons Aged ≥18 Years, by Age Group — United States, 2008–2009 and 2016–2017.” Centers for Disease Control and Prevention. 

  4. 2019 National Survey on Drug Use and Health.” Substance Abuse and Mental Health Services Administration.

  5. Drugs, Brains, and Behavior: The Science of Addiction.” National Institute on Drug Abuse.

  6. Physical and Psychological Effects of Substance Use.” National Center on Substance Abuse and Child Welfare.

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