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How to Tell If Someone is on Drugs
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How to Tell If Someone is on Drugs

Written by Seth Fletcher on April 26, 2024
Medical editor Dr. Chintan Shah
Last update: April 29, 2024

The signs of drug use and addiction in adults are not as common as most people think. Movies and media depictions often paint misleading representations of how a person on drugs should look or behave. People who abuse drugs may go on with their behaviour for a long time without being discovered. Almost 18% of Canadians report that they have used an illegal drug at some point in their lifetime. 

Do you suspect someone you know has a drug addiction? Are they exhibiting addictive behaviour? Maybe it’s your best friend, your spouse, or even your parents. People who start using drugs recreationally may discover that they want to use them even when they’re not with friends, at a party, or have any real reason to use them. They will often refuse to acknowledge their problems and deny them if confronted. 

If you are worried that a loved one or someone close to you is on drugs, there are warning signs of substance abuse to look out for. The Canadian Centre for Addictions explains how to tell if someone’s high on drugs and how to help someone with addiction

Key Takeaways

  • People who abuse drugs can go on for long without being detected
  • There are signs to look out for if you think someone you know is abusing drugs
  • These signs of drug use could be physical or behavioural
  • You may need professional intervention to get a drug user to seek or accept help

Drug Abuse vs. Addiction

Drug abuse and drug addiction are not the same thing, even though they’re often confused. Drug abuse is the misuse of drugs, which can include using drugs recreationally or without a prescription. Drug addiction, on the other hand, is a more severe condition characterized by a compulsion to use drugs despite negative consequences. 

Addiction occurs once someone develops a tolerance and becomes dependent on a substance. Drug abuse is a choice, while drug addiction is a mental illness. It’s also worth stating that drug abuse is what leads to drug addiction. So, the key difference between drug abuse and addiction is the level of compulsion involved. People who use drugs may be able to control their use, even if it’s causing problems in their lives. Those with addiction have a compulsive need to use drugs and cannot stop unless they get help. 

Signs and Symptoms of Drug Use

There are substance abuse signs and symptoms that could indicate that someone is struggling with drugs. These signs could be physical or behavioural: 

Physical Signs of Drug Use

  • Appetite Changes

Drug use can lead to appetite changes. Some drugs, like stimulants, can suppress appetite and cause weight loss. Other drugs like cannabis may increase appetite and lead to weight gain. Appetite changes can also be due to underlying disorders like depression or anxiety, which are common co-occurring disorders with drug use. 

  • Bloodshot Eyes

Bloodshot eyes are a common physical sign of drug use. You may notice bloodshot eyes in users of marijuana, amphetamines, cocaine, and opioids. 

  • Constricted or Dilated Pupils

Different drugs can cause the pupils to react in various ways. Stimulants like methamphetamine and cocaine can cause the pupils to dilate, while heroin and other opioids can cause them to constrict. These changes in the pupils result from how the drugs affect the nervous system. 

  • Runny nose/Nosebleeds

A runny nose and nosebleeds can possibly be one of the signs of cocaine use. Other drugs like methamphetamine, heroin, or prescription pills, which are also snorted, can cause a runny nose. Snorting irritates the nasal lining and can cause inflammation. Some opioids can cause the nasal lining to dry out and crack, leading to nosebleeds. 

  • Poor Hygiene or Grooming Habits

A change in appearance is one of the common drug use symptoms. Drug use can cause people to neglect personal hygiene and grooming. Dirty clothes, body odour, or an unkempt look could be because an individual is struggling with substance use. People especially pay less attention to their hygiene when they use drugs that cause them to be drowsy or apathetic. 

  • Slurred Speech

Some drugs can slow down the nervous system, delaying their reaction time and slurring their speech. Slurred speech can be one of the signs that someone is high and may be caused by both short and long-term drug use. Other signs like poor coordination or concentration difficulties may also accompany it.  

  • Presence of Drug Paraphernalia 

Drug paraphernalia is any object or tool used to take drugs. They could include things like pipes, bongs, syringes, rolling paper, and scales. If you find drug paraphernalia in a loved one’s possession, it could be an indicator that they’re using drugs. 

  • Needle or Track Marks

Needle or track marks are small circular marks on the skin caused by repeated injections of drugs or drugs with a needle. Track marks may appear on the arms, legs, or other parts of the body and may be accompanied by bruising, scarring, or scabbing. 

Behavioural Signs of Drug Use

  • Changes in Sleep Patterns

Drug use may lead to a disruption in sleep patterns. A person on drugs may sleep too much or too little, have trouble falling or staying, or experience unusual dreams. These disruptions occur due to the effects of drugs on the mind and body. They can also be one of the symptoms of withdrawal from drugs

  • Fluctuating Energy Levels

Drug use can lead to periods of fluctuating energy levels, typically marked by periods of intense energy followed by periods of lethargy or being wide awake at night and sleepy during the day. These fluctuations can be caused by the drug's effects on the body and can make it difficult to perform normal activities. 

  • Changes in Mood

Drug use can cause mood changes ranging from mild to severe. These changes can include euphoria, sadness, depression, and anxiety. They occur due to the effects of drugs on the brain and can affect a drug user or addict’s relationships.  

  • Anxiety

A common answer to the question of why people do drugs is to deal with feelings of anxiety and stress. However, drug use can cause or worsen feelings of worry, fear, or panic not related to any specific situation or event. In some cases, anxiety may be so severe that it affects one’s ability to function normally. 

  • Lack of Motivation

Drug use can also lead to a decline or loss of motivation. A person on drugs may lose interest in school, work, or previously enjoyed activities. They may have difficulty completing simple tasks, display a lack of interest in life or a sense of hopelessness. This lack of motivation can seriously impact a person’s ability to function and can lead to feelings of despair and isolation. 

  • Decline in Work or Academic Performance

Drug use can also cause a decline in academic or work performance. A person doing drugs may skip classes or work. They may also struggle to focus or follow instructions, which can lead to avoidable mistakes. This decline can have significant consequences like job loss or academic failure. 

  • Irritability and Aggression

Irritability and aggression are common signs of drug abuse that manifest in various ways, such as mood swings, arguments, and sudden outbursts. Aggression can also include verbal or physical violence, property damage, and threatening behaviour. This type of conduct can be distressing to those close to the person using drugs. 

  • Difficulty Concentrating or Memory Loss

The impact of drug use on the mind can lead to difficulty concentrating and memory loss. People who use drugs may struggle to focus on tasks, remember things, or process new information. These effects can be frustrating and can diminish a person’s ability to function at work or school. It can also lead to difficulties in social situations and cause relationship problems. 

  • Financial or Legal Troubles

Drugs are costly to obtain, and using them can lead to a plethora of financial and legal troubles. People who do drugs may miss work and struggle to pay bills, get into debt, or steal money from others. They could also get arrested for possessing illegal drugs or driving while intoxicated. These types of difficulties could be challenging to handle and can have long-term consequences. 

Signs and Symptoms of Different Types of Substance Abuse

The signs and symptoms of substance abuse a person will manifest depend on the specific drugs they abuse. Here are some of the most misused drugs and the common signs of abuse:


Cannabis, also known as marijuana, is a drug obtained from the cannabis plant. It can be smoked, vaped, or ingested in other ways. Cannabis abuse signs and symptoms include:

  • Dry mouth
  • Bloodshot eyes
  • Poor coordination 
  • Fatigue
  • Increased appetite
  • Reckless or dangerous behaviour
  • Memory impairment
  • Weight gain
  • Nervousness or paranoia


Opioids are a class of drugs obtained from the opium plant or manufactured synthetically. They are prescribed for pain but often obtained illegally. Examples of opioids include morphine, tramadol, codeine, heroin, oxycodone, hydrocodone, and fentanyl. Signs and symptoms of opioid abuse include:

  • Drowsiness
  • Mood swings
  • Irritability 
  • Anxiety
  • Insomnia
  • Constipation
  • Hallucinations
  • Exhaustion
  • Loss of motivation
  • Forging prescriptions 
  • Decreased work or academic performance


Alcohol is a legal substance consumed in the form of beer, wine, or liquor. Its social acceptability makes it one of the most abused drugs in the world. Signs and symptoms of alcohol abuse include: 

  • Memory blackouts
  • Lack of coordination 
  • Nystagmus (rapid, uncontrolled eye movements)
  • Sweating
  • Increased heart rate
  • Changes in appearance
  • Mood swings
  • Difficulty controlling drinking
  • Impaired judgment
  • Depression and anxiety
  • Frequent falls or accidents
  • Diminished work or academic performance


Cocaine is a highly addictive stimulant drug that is snorted, smoked, or injected. It is obtained from the leaves of the coca plant and can be processed into a more potent form known as crack. Signs and symptoms of cocaine abuse include: 

  • Excitability 
  • Risky behaviour
  • Mood swings
  • Increased confidence
  • Hallucinations 
  • Paranoid thinking or behaviour
  • Agitation/restlessness
  • Changes in sleeping and eating patterns
  • Nosebleeds/runny nose
  • Social isolation
  • Changes in appearance

Prescription Pills

Prescription pills are medications prescribed by a doctor, but they can be abused when used without a valid prescription. Examples of commonly abused prescription pills include benzodiazepines, barbiturates, stimulants, and sedatives. Signs and symptoms of prescription pill abuse include:

  • Drowsiness
  • Confusion
  • Unsteady gait
  • Slurred speech
  • Difficulty concentrating
  • Increased alertness
  • Irregular heartbeat
  • Anxiety 
  • Paranoia
  • Appetite changes
  • Forging prescriptions 
  • Requesting early refills 
  • Seeking prescriptions from multiple prescribers


Methamphetamine, or meth, is a powerful and addictive stimulant drug. It is a stimulant drug that is smoked, snorted, or injected for the euphoric burst of energy and excitement it brings. Some signs and symptoms of methamphetamine abuse include: 

  • Confusion 
  • Psychosis
  • Seizures
  • Chest pain
  • Hallucinations
  • Weight loss
  • Mood changes
  • Violent behaviour
  • Poor coordination 

Tips on How to Confront Someone Who’s Abusing Drugs

People who abuse drugs tend to deny or react negatively when confronted about the situation. If someone you care about is abusing drugs, it’s essential to be respectful, non-judgmental, and understanding when you talk to them. You may need to initiate an intervention if your approach does not yield any positive results. 

So, what is an intervention? An intervention is a structured and planned process of meeting a person abusing substances or struggling with addiction and getting them to see the need for help and support. 

Here are some tips to increase your chance of success when confronting someone abusing substances:

  • Prepare an intervention team
  • Choose a suitable time and location
  • Plan what to say before the time
  • Have resources for substance abuse and addiction recovery ready
  • Manage your expectations and prepare for every outcome
  • Set ultimatums and stick to them
  • Request for an immediate decision at the end of the intervention
  • If they respond positively, follow them up to ensure they stick to their treatment plan

When to Consult a Professional

You should seek professional help concerning your or a loved one’s drug use if you notice the following: 

  • Using the substance of abuse in increasing amounts
  • Having work or academic problems due to substance abuse
  • Getting into financial or legal troubles due to substance abuse
  • Trying and failing to stop abusing the substance
  • Develop physical or mental health problems due to substance use 
  • Developing tolerance to the substance – needing more to get the same effects
  • Having withdrawal symptoms upon cessation or reduction of substance use

If you are wondering how to help someone with addiction and substance abuse issues, the Canadian Centre for Addictions can help. At CCFA, we offer drug addiction treatment in an environment that inspires lasting change. Our team of professionals uses individualized treatment strategies to help clients break out of the cycle of addiction and drug use. Call 1-855-499-9446 today to learn more about our services.


What are some good questions to ask about drugs?

Some good questions to ask when talking to someone about drugs are:
• How often do you use drugs?
• How much do you use?
• When did you start using drugs?
• Do you ever feel like you need to use drugs to feel normal?
• Have you tried to stop or reduce your drug use?
• Are you concerned about how much of the drug you use?

Can we predict addiction?

We cannot predict with certainty whether someone will become addicted to a substance. However, some factors can increase a person’s likelihood of addiction. They include:
• Family history
• Personal history of mental illness or trauma
• Early exposure to drugs and/or previous addiction history
• Social and environmental factors

Does addiction start in the brain?

Research shows that addiction starts in the brain. When a person uses drugs, the brain’s pleasure and reward system is activated. Over time, the brain can become dependent on the neurotransmitters triggered by the substance of abuse, causing the user to crave more of the drug. The cravings lead to tolerance and addiction.

How can we prevent drug abuse in youth?

Some practical ways to prevent drug abuse in youths include:
• Educating them on the dangers of drug use
• Teaching the youths about peer pressure and how to resist
• Provide opportunities for positive social interaction
• Helping young people develop self-esteem and confidence
• Encouraging healthy alternatives to drugs like sports and hobbies
• Being a positive role model for young people

What are ten ways to say no to drugs?

• Be direct and firm in your refusal
• Provide a reason for why you don’t want to do drugs
• Have a plan for what to do instead of using drugs
• Avoid places where you might be offered drugs
• Walk away if your refusal is ignored
• Remind the other party about the dangers of drug use
• Change the subject if possible
• Learn and relay statistics about the risks of drug use
• Change your circle of friends if necessary
• Offer to be the designated driver

Certified Addiction Counsellor

Seth brings many years of professional experience working the front lines of addiction in both the government and privatized sectors.

Dr. Chintan is a Board Certified Family Physician with an interest in holistic and preventative care as well as healthcare systems. Credentialed Physician with both American & Canadian Board of Family Medicine. Adjunct Professor in the Department of Family Medicine at the Schulich School of Medicine & Dentistry. Telemedicine clinician.

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