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Alcohol & Other Drugs

Learn About Opioids


Author: Canadian Institute for Substance Use Research


For references to the studies discussed in this info sheet, see the reference list.

What are opioids?

Opioids are psychoactive (mind-altering) drugs that alter our perceptions of pain and slow down our breathing, heart rate, thoughts and actions. They are called opioids because they either are derived from the opium poppy or produced from chemicals to provide or intensify the effects of natural opium. There are many different opioids, including morphine, heroin and codeine (e.g., Tylenol 3). They can be manufactured in regulated labs and used for medical treatment in and outside of hospitals, for example prescription drugs like oxycodone (e.g., Percocet) and fentanyl. But they can also be made in illicit labs by people with varying degrees of competence. Drugs made in illicit labs, even those that look like pills available from pharmacies, are often impure and vary in strength. This means opioids purchased illegally can be very dangerous.


Why do we use opioids?

People use opioids for a variety of reasons. Some people use opioids for pain treatment or for temporary relief from anxiety, adverse experiences or difficult life circumstances. Others use opioids to experience a feeling of euphoria or out of curiosity about drugs that are perceived as risky and out of the mainstream. And still others use prescription opioids (e.g., methadone) to help reduce dependence on street opioids. Some unintentionally expose themselves to opioids mixed into another type of drug they buy from an unregulated supplier. Like all drugs, opioids can be harmful.

Using an opioid may help us feel more comfortable at a party, but repeatedly using the drug to address social anxiety may lead to harms to our health or relationships. And, while fentanyl and other prescription opioids are safe when used in ways that are well managed, it is impossible to manage the risks related to opioids obtained through an uncontrolled supply chain. Many people choose not to use opioids (or other drugs) manufactured in illicit labs because they can’t be certain about the contents and dosage of the drug they are taking.


What happens when we use opioids?

When swallowed, opioids are absorbed into the bloodstream through the stomach and small intestine. When an opioid is injected, the drug goes directly into the bloodstream. Sometimes opioids are snorted or smoked. When snorted, the drug is absorbed into the bloodstream through membranes in the nose, and when smoked, it is absorbed across the lining in the lungs. Once in the bloodstream, the drug travels to the brain. In our brain, opioids mimic painkilling chemicals the body produces naturally when injured.

The effects of opioids can be different for different people. One person may feel relaxed and drowsy while another may feel talkative and energetic. A lot depends on the amount we use at a given time and whether we have also consumed alcohol or other drugs. Other factors that influence how opioids will affect us include our

  • past experiences with the drug,

  • present mood and surroundings, and

  • mental and physical health condition.

Impact on well-being

Opioids can have positive effects but the drugs can also be harmful to our well-being. Small amounts of an opioid may help to soothe pain or anxiety. But using larger amounts, or even small amounts with high concentrations, may lead to extreme drowsiness or overdose. Not everyone who overdoses will die, but drug-induced comas increase the risk of negative effects on the brain.

People sometimes use opioids over the long term because they find the drugs helpful for managing ongoing health problems like chronic pain. But making good decisions about using an opioid involves regular consultations with a healthcare professional and weighing the benefits and risks of continuing use. For instance, while pain itself may impact our ability to remember and learn things, over time regular use of opioids is linked to a decline in cognitive functions including verbal fluency, memory and decision-making. It is not clear if these deficits may improve when use is stopped.

Whenever we choose to use an opioid, it is important to remember the potential risks involved in obtaining a drug outside of a regulated system. Purchasing any drug in an unregulated market is always risky because we can never know for sure what we are buying. Due to shortages of street heroin in the supply chain, illicit manufacturers may turn to fentanyl or other drugs as a substitute. Unless we have access to checking/testing kits (which are not 100% accurate), we have no idea what is in the drugs we buy or how much. Since it is not possible to know the purity of the drug, we can accidentally use too much.

Signs of overdose

Opioids affect our breathing, and death from overdose is usually the result of respiratory arrest.

Signs of overdose include:

  • slow, shallow, irregular or no breathing

  • slow or no pulse

  • unusual snoring, gurgling sounds, choking

  • unresponsive, can't be woken up

  • blue lips or nails, pale, cool skin

  • tiny pupils

  • vomiting

The current best response for an opioid overdose is the administration of naloxone, an antidote drug that can help reverse the effects of an opioid overdose by restoring breathing.

If someone you know is showing signs of an opioid overdose, call 911 right away. (The Good Samaritan Drug Overdose Act exempts people at the scene of an overdose from being charged for personal use of an illegal substance, as well as from being charged for breach of probation or parole.)

Try to wake the person up. If the person does not regain consciousness, use naloxone if available (and if you are trained to give it).

After a naloxone injection, a person might feel sick. This feeling will go away when naloxone wears off in about 30-90 minutes. Be aware, if the opioid is still working through the person’s system the overdose may return and more doses of naloxone may be needed.

Stay with the person until paramedics arrive. If you must leave them alone or if the person is unconscious, roll them onto their side into the recovery position so they won't choke if they throw up.

When is using opioids a problem?

Using opioids is a problem when it negatively affects our life or the lives of others. Many of us may think this refers only to people who regularly use opioids, but even a single occasion of use can lead to a problem. For instance, if we share needles or straws, we increase our risk of infections and blood-borne diseases that may lead to problems of the heart, lungs and liver. Or the wrong dose could lead to a fatal overdose. What's important to recognize is the potential for adverse consequences of use in any context and over time.

One consequence that can develop is tolerance—that is, it takes more of the drug to achieve the positive effects. If we develop tolerance to an opioid and stop using it, our tolerance is reduced. Overdose can happen if we try to use the same amount as before we stopped. If we use opioids regularly, we can develop another type of problem—dependence. This means feeling like we need the drug to function and feel normal.

The reasons people use opioids influence their risk of developing problems. For instance, if a person uses an opioid out of curiosity, only occasional social use may follow. But when a person uses opioids to cope with a long-term problem, then more long-lasting and intense use may follow.

People who develop a dependence on opioids can experience signs of withdrawal—hot and cold sweats, stomach cramps, muscular spasms, diarrhea—within 6 to 12 hours of last using the drug. The severity of the withdrawal symptoms may be influenced by factors such as the person's general health and how long they have been regularly using the drug. Because symptoms can be strong and unpleasant, some people continue using the opioids even when they don’t want to.

Mixing opioids with other substances

People sometimes mix opioids with other substances to experience different feelings or to offset the effects. For instance, a person may use an opioid to help them relax and rest after using cocaine, or use cocaine to reduce the negative effects of withdrawal from an opioid. But combining substances is risky as they can act in unexpected ways. The following are some common combinations and possible results.

Alcohol and other depressants. These are substances that slow down our heart rate and make us feel more relaxed. Since opioids are depressants, using the drug with other depressants can intensify these effects and increase our chance of overdose or death.

Stimulants. These are substances, such as energy drinks and cocaine, which increase our heart rate and make us feel more energetic. When combined with opioids, they may mask the depressant effects. This can cloud our judgment about how intoxicated we are and lead to riskier behaviours. Combining opioids and stimulants (e.g., cocaine and heroin) can also increase our chance of overdose.

Cannabis. Combining cannabis with opioids may mask the effects of each drug. This may lessen our control over our behaviour, increasing the chance we may take risks that result in problems.

Medications. When prescription or over-the-counter medications are used with opioids, there is the potential for side effects or for the medicinal benefits to cancel out. There is also risk of overdose. Taking the time to read medication labels or consulting with a healthcare professional can reduce these risks.


How to make healthier choices about opioids

Whenever we decide to use opioids, it is helpful to know what steps we can take to ensure our use is the least harmful possible. Some of the risks of using opioids are related to how we use it. For example, injecting the drug (or any drug) can lead to infection and transmission of disease if we share needles. The following are some other useful guidelines to follow.

Not too much. Monitoring how much we use in a given period helps us reduce the risk of overdose and other harms to our health.

Tips: Always follow the dose instructions when using a prescribed opioid. If you choose to use illicit drugs, start with a small amount whenever you get a new supply.

Not too often. Understanding our pattern of use helps us to manage the risks.

Tips: Reflect on how often you use an opioid and the reasons you use. If you think you are using more often than makes sense, you may want to consider some changes (the resources below offer a place to start). Check with your healthcare professional if you are not feeling the positive effects of a prescribed opioid. Using a drug more frequently than prescribed may be dangerous.

Only in safe contexts. Feeling safe and making informed decisions about situations where an opioid may be used helps to minimize harms.

Tips: Check with your healthcare professional about the effects of a prescribed opioid on physical and mental functioning. Find a buddy or use overdose prevention sites or supervised consumption sites if available (using a street opioid alone means no one will be there to help you if you overdose).


Legal status

Prescription opioids are legal when they are prescribed by an authorized healthcare professional and used by the person for whom they are prescribed. Illegal possession of opioids and trafficking, importing, exporting or producing opioids can result in imprisonment.


What to do if you or someone you know wants to explore change

To better understand how substances play a role in your life, consult the You and Substance Use Workbook on the Here to Help website: This website also features detailed information on substance use and mental health.

You can also find information about a wide variety of substance use issues on the Canadian Institute for Substance Use Research


For information on treatment options and resources throughout BC, call the Alcohol and Drug Information and Referral Service at 1-800-663-1441. In Greater Vancouver, call 604-660-9382.


About the author

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The Canadian Institute for Substance Use Research, formerly CARBC, is a member of the BC Partners for Mental Health and Substance Use Information. The institute is dedicated to the study of substance use in support of community-wide efforts aimed at providing all people with access to healthier lives, whether using substances or not. For more, visit


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