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Types of Substances

There are many types of substances including alcohol, depressants, hallucinogens, opioids and stimulants. Each have varying effects that can cause reactions, and require different ways to reduce harm when taking them. Read this section to learn about the types of substances and how each can affect the human body. Find out what to do to keep yourself safe if an overdose happens.

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More information on stimulants or uppers


Desired effects

The effects many people look for from stimulants are:

  • feeling euphoric or very happy
  • having more energy
  • feeling more confident
  • having more sex drive
  • feeling more pleasure with sex
  • being able to stay awake
  • feeling “disinhibited” or confident, powerful and energetic
  • losing weight
  • finishing or staying focused on school or work

(Note: ADHD medication can have the opposite effect of traditional stimulants when used correctly. They can make people diagnosed with ADHD feel calmer and more focused).

Signs of being high or intoxicated

Stimulants can make people feel high. Stimulant intoxication happens when a stimulant drug makes a person’s reactions heightened or exaggerated. They may seem to have bigger reactions than usual, like being more aware (hyperaware). They may be more sexual (hypersexual) and more alert to possible threats (hypervigilant). They may also feel restless and anxious and move a lot without meaning to (psychomotor agitation).

Overdose or drug poisoning

Signs of overdose can include:

  • having a very high body temperature (hyperthermia)
  • seeing or hearing things that aren’t there (becoming paranoid or psychotic) or hallucinating
  • having seizures, sweats, bad headaches
  • needing to urinate (pee) more often
  • feeling anxious and agitated

Overamping is used to describe overdosing on speed or cocaine. It can happen regardless of the amount the person takes or how long they’ve been using the drug. In other words, there isn’t really a set amount of a drug that can cause an overdose. It can result from many things like:

  • not sleeping
  • being exhausted from not having enough to eat or drink
  • being with people who make you feel uncomfortable
  • having taken too many hits

Stimulant toxicity is a condition that can happen when you take stimulants. It is a medical emergency and is life-threatening. It may cause organ damage, seizures, heart attack, stroke, kidney failure, etc.

While the effects of overdosing on cocaine are similar to what happens with speed (amphetamine), coke (cocaine) is more likely to cause strokes, heart attacks, and seizures.

Withdrawal symptoms

Withdrawal is what happens when you stop using substances suddenly after you’ve been using them regularly. It’s important to remember that withdrawal symptoms are the opposite of the high you feel when using the substance. The withdrawal symptoms for stimulants include an excessive need for sleep and an increase in appetite and cravings. People also often have little energy and feel depressed.

Harm reduction tips

Tips to reduce harm when using stimulants include:

  • use less
  • use at safe injection sites
  • use clean needles and supplies or gear
  • get your drugs tested to see if they are mixed with other contaminants such as fentanyl or dangerous chemicals

For general safety tips, see The Basics section.

For more information on vaping, check out the following links: Vaping and the Myths and Facts of Vaping and Tobacco.

Depressants or downers

Examples – alcohol, benzos (Xanax, Valium), GHB

Depressants are downers. They slow down the messages sent to and received between the central nervous system and the brain.

Alcohol add

People may choose to drink for many different desired effects. Some may want to relieve pain or feel good. Others may drink to help them relax and cope better or be more comfortable in social situations. But alcohol affects everyone differently, so what may be too much for one person may not be for someone else. Intoxication, or drinking too much may also produce other less desirable effects. Some people get very tired or drowsy and have slower reflexes and reactions. Others become aggressive or angry in a way that might not be normal for them. Some people slur their speech or vomit. Other possible effects include difficulty walking straight, being confused and losing a sense of what they would ‘normally’ not do (disinhibition).

Overdose or drug poisoning
Signs of overdose or drug poisoning from alcohol can include:

  • losing consciousness
  • difficulty breathing (respiratory depression)
  • passing out from loss of oxygen (asphyxiation)
  • forgetting things that happened when drunk (“alcohol blackout”)
  • coma

Withdrawal symptoms
Withdrawal is what happens when you stop using substances suddenly after you’ve been using them regularly. Withdrawal symptoms from alcohol include feeling anxious, agitated or depressed. Other signs are falling asleep, shaking, sweating, vomiting, hallucinating and dehydration. Withdrawal symptoms are different from having a hangover, which may occur after a big night of heavy drinking (binge drinking – 5 or more standard drinks for a biological male and 4 or more standard drinks for a biological female).



Benzodiazepines or benzos, such as Xanax and Valium, are sedatives or tranquilizers. They are sometimes prescribed to relax tight muscles, treat alcohol withdrawal, or manage seizures. They are also used to sedate people before surgery or dental procedures. Some people may be using benzos for insomnia or anxiety, even though they are no longer the recommended first treatment option.

Overdose or drug poisoning

Benzos can be dangerous when mixed with other drugs like methadone (opioids). Signs of overdose include extreme sedation and a type of amnesia that won’t let you form new memories (anterograde amnesia). It is safe to use benzos when they are prescribed for you and used only occasionally or for short periods of time.

Like any drug, benzos can become addictive if they are used more regularly. A person may start to crave the drug or need to take a higher dose as their tolerance increases (they need more and more of the drug to have the same effect).

Withdrawal symptoms

If you use benzos regularly and then stop suddenly, you may have withdrawal symptoms. These can include headaches, insomnia, difficulty concentrating, tremors and loss of appetite. If you stop using benzos after regular use of high doses, you may experience seizures, delirium (confused thinking), agitation or paranoia (like believing you are being threatened when you aren’t).



GHB is sometimes referred to as Gina, G, or Tina (when it is mixed with crystal meth). It is a powerful sedative that can cause someone to become unconscious or go into a deep sleep. It can be very dangerous and lead to death when taken with alcohol or other drugs. In the 1990s, GHB was referred to as a “club drug” and more recently as a “date rape drug,” referring to incidents when it has been secretly slipped into peoples’ drinks so they became unconscious and not able to remember or resist a sexual assault.

Overdose or drug poisoning

With GHB, there is only a small difference between a dose that produces a wanted effect and a dose that causes an overdose. A little too much of this drug can be fatal. Combining GHB with alcohol or other drugs increases the risk of overdose and other dangerous effects, including death.

Withdrawal symptoms

GHB is addictive and can lead to tolerance and physical dependence. Physical dependence is when your body needs the drug in order to feel normal, think clearly and stop withdrawal symptoms. You can go into withdrawal if you stop using the drug suddenly. Withdrawal symptoms can include anxiety, tremors, an inability to sleep and other unpleasant, dangerous effects, including paranoia with hallucinations and high blood pressure.

Harm reduction tips


Ways to reduce harm depend on what kind of downer the person is taking. For general safety tips, see The Basics section.

For alcohol:

  • Avoid drinking on an empty stomach. Eat food and drink water before and while you are drinking alcohol
  • Avoid drinking games that may cause you to consume a large amount of alcohol in a short period of time
  • Try switching every second drink for something non-alcoholic, like pop, kombucha or a mocktail
  • Don’t drink if you are using medication that interacts with alcohol (check out for more information)

For benzos:

Don’t mix with other downers. “Benzo dope” (opioids mixed with non-prescribed benzodiazepines) in unregulated street drugs have been discovered to contain a lethal combination of opioids and benzos.

For GHB:

Don’t use alone. Begin with a tiny test amount before taking more. Do not take GHB with alcohol or other drugs.

Opioids or pain pills

Examples –  fentanyl, down, heroin, Dilaudid (Dillies), Oxycodone & Percocet (also known as Oxys & Percs)

Opioid medications are generally prescribed to help people manage pain and can give those living with severe pain a better quality of life. They are also available in over-the-counter medication in a much milder form that doesn’t require a prescription, like Tylenol 1s. But these drugs can also lead to potential harm.

Regular use may cause unintended harm, such as:

  • driving under the influence (DUI)
  • missing work
  • hurting important relationships

Regular opioid use can lead to physical or emotional dependence and overdose.

More information on opioids or pain pills


Overdose or drug poisoning

Opioids change the way people experience pain. They slow down breathing, heart rate, thoughts and actions. If a person takes more than their body can handle (tolerate), they may stop responding and become unconscious. An overdose can lead to death because the drug interferes with the parts of the brain that are responsible for breathing.

It is difficult to say how much of a drug can cause an overdose. It depends on many things, like which drug, how much and how often. It is affected by what your body is used to (level of tolerance).

Overdoses are often caused by:

  • taking large doses often
  • injecting the drug
  • taking an opioid while also using sleeping pills, benzos or muscle relaxants
  • using when you also have other health conditions (breathing difficulties, kidney or liver disease)

To learn more, there is more information on how to recognize and respond to an overdose.

Withdrawal symptoms

Withdrawal symptoms with opioid use include nausea, headaches, nervousness, anxiety and irritability. People often experience alternating chills, goosebumps and muscle pain. They become obsessed with getting the drug.

Harm reduction tips

Harm reduction tips for opioids include:

  • not using alone
  • having a naloxone kit on hand and understanding how to use it
  • not mixing with alcohol or other drugs
  • taking a small amount first to see how strong it is

Hallucinogens or psychedelics

Examples – cannabis, LSD, MDMA (Molly or Ecstasy), ketamine, magic mushrooms

[Note: MDMA (Molly or Ecstasy) is both a stimulant and a hallucinogen. For more information on MDMA, read the Stimulant or uppers section]

Many different drugs are classified as hallucinogens or “psychedelics”. These substances change the way you see, hear, taste, smell or feel. They alter mood and thought. How they make people feel depends on which drug it is, how much the person is using and how often. It also depends on your age, physical or mental health, and if you are also using alcohol or other drugs (which includes everything from prescription to over-the-counter drugs and herbal remedies).

It is important to note that the setting has a great effect on your reaction when you take hallucinogenic drugs. The experience can be more problematic when you can’t control where, when and how you are using these types of drugs. You may feel fear and anxiety. These drugs are consumed more comfortably in a controlled, calm environment, with trusted friends. However, it’s important to know the exact drugs you are using and what doses you are having. It’s hard to predict how anyone may react to these drugs so start slow and don’t mix.

Hallucinogens are commonly divided into two groups,

  • classic hallucinogens, such as LSD, magic mushrooms (psilocybin) and MDMA (Molly or Ecstasy)
  • dissociative hallucinogens, such as ketamine

Some hallucinogens are synthetic and some are not. The chart below describes withdrawal symptoms, and what happens if you get high or intoxicated.

Cannabis add

Cannabis is the scientific name for the hemp plant. Its leaves and flowers—often called marijuana—contain a psychoactive resin that can affect how we think, feel and act. Cannabis may come as:

  • marijuana (dried leaves and flowers or ‘buds’)
  • hashish or hash (pressed resin from flowers and leaves) or
  • hash oil (concentrated resin extracted with a solvent)

Cannabis is usually smoked, but it can also be vaporized or consumed through food, a drink or a concentrate. The effects of cannabis can be very different for different people. One person may feel relaxed, another full of energy, and another anxious. Sometimes the same person will have a different experience on a different occasion. A lot depends on the type, amount and plant strain you use at a given time. Other things affect how you respond include past experiences with cannabis use and your present mood and surroundings. Your response also depends on your biochemistry, mood or mindset, mental and physical health and diet.

Many people who use cannabis socially say it helps them relax and increases their sense of well-being. But some people may feel anxious after using cannabis which can affect their interactions with others. And for a few hours after smoking a joint, a person may have a hard time remembering things, which may have an impact on friendships. Cannabis use can also increase the risk of making bad decisions, such as driving before the effects have completely worn off. And while cannabis may help to relieve stress or anxiety, continuing to use it as a coping strategy may harm our health and relationships. Regular use of cannabis by young people has particular risks. Cannabis can interfere with normal brain development, as do other psychoactive drugs. Early use can also interfere with developing normal patterns of social interaction with our peers. For more information on your relationship with Cannabis, check out the following link: Cannabis and You.

Overdose or drug poisoning


The chance of overdose depends on which drug it is, and how much the person has taken. Cannabis hyperemesis syndrome is a rare condition that can occur in people who use cannabis daily over a long period. It can cause severe vomiting, as well as other symptoms like nausea and stomach or abdominal pain.

The use of cannabis has been linked to psychotic symptoms or psychosis for a small number of people. Psychosis may be thought of as a break with reality. Symptoms include experiencing thoughts, feelings, sounds or seeing things (hallucinations) that others around you do not experience. It becomes difficult to know what is real and what is not. For most people, these symptoms go away as the drug wears off after several hours, and their thinking, feeling and perception return to normal. The symptoms do not usually return unless cannabis is used again. But, you are at high risk of more serious problems if you have a family member with psychosis or schizophrenia, and especially if you also develop a temporary psychosis when using cannabis. It is very important to talk with a healthcare provider about your use if you are at risk.

Overdose is more likely with dissociative hallucinogens. For example, large amounts of PCP can lead to coma, seizures and death. Regardless of the type of hallucinogen, a risk for overdose is produced by the drugs’ effect on people’s judgment and mood. For example, people on psychedelics may lose their sense of reality and make risky decisions, which may cause them to do things they wouldn’t normally do. Doing things they wouldn’t normally do can create opportunities for these drugs to place people in situations which may put their lives at risk. Psychedelics can also be poisonous when mixed with contaminants, such as other drugs.

Harm reduction tips

For harm reduction tips to avoid overdose and other severe symptoms, see safety tips in The Basics section.

The substances and the information we’ve included are just the tip of the iceberg. There are many other substances that exist and more information is available to learn about them. It’s important to always think carefully about the source of the information to make sure it is accurate. Resources like CAMH and Drug Cocktails are great for looking up specific substances quickly.

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