Learn About Heroin

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Author: Canadian Institute for Substance Use Research


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

What is heroin?

Heroin is a psychoactive (mind-altering) drug that affects the way we think and behave. It is a depressant that slows down our breathing, heart rate, thoughts and actions.

Heroin is made from the chemical processing of morphine, a drug derived from the opium poppy plant. Originally manufactured as a pain medication, most of the heroin available in Canada today comes from uncontrolled labs. The drug is often mixed with other substances and comes in different forms—a white powder, a brown and lumpy substance, or a dark sticky gum. It can be snorted (e.g., sniffed through a straw) or dissolved in water and injected. It can also be smoked.


Why do we use heroin?

Since the late 19th century, people have been using heroin for various reasons. For some people, heroin has served as a medicinal tool for relieving physical pain. For others, it has been used for temporary relief from trauma, anxiety or difficult life circumstances. Some have used heroin to feel relaxed and connect with others. And still others have used it out of curiosity about a drug that is perceived as risky and out of the mainstream. But like other drugs, heroin can be harmful.

Many people choose not to use heroin or to use the drug in moderation, because being less in control of their behaviour increases the likelihood of making unwise choices such as having unsafe sex. Using heroin 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.


What happens when we use heroin?

When snorted, heroin is absorbed into the bloodstream through membranes in the nose, and when smoked, it is absorbed across the lining in the lungs. When injected, it goes directly into the bloodstream. Once in the bloodstream, heroin travels to the brain. In our brain, heroin mimics painkilling chemicals the body produces naturally when injured.

The effects of heroin 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 of heroin we use at a given time and whether we have also consumed other drugs or alcohol. Other factors that influence how heroin will affect us include our

  • past experiences with the drug,

  • present mood and surroundings, and

  • mental and physical health condition.

Impact on well-being

Sometimes, when we think about heroin, we forget that it once served as a medicine to relieve severe pain and cough. This may be because of the potential for harms involved in using the drug. Small amounts of heroin may help to soothe pain or anxiety. But using larger amounts, or small amounts in higher concentrations, may lead to extreme drowsiness or overdose. And purchasing any drug in an unregulated market is always risky because we can never know for sure what we are using or buying.

Drug-induced comas increase the risk of negative effects on the brain. And regular use of heroin is linked with a decline in some cognitive functions, including decision-making and verbal fluency. It is not clear if these deficits may improve when use is stopped. A woman who regularly uses heroin while pregnant may give birth prematurely and have a baby with a low birth weight. Sharing drug-use equipment is associated with infections and blood-borne diseases that may lead to problems of the heart, lungs and liver.

Signs of overdose

Using heroin involves a risk of overdose. How much and how often we use it affects our degree of risk. And since it is usually not possible to know the purity of the drug, we can accidentally use too much. Heroin affects our breathing, and death from overdose is usually the result of respiratory arrest. Signs of overdose include:

  • slow or no breathing

  • slow or no pulse

  • pale, cool skin

  • vomiting

If someone you know is showing signs of overdose, call 911 right away. Remain with the person. Try to wake them up. If they do not regain consciousness, roll them onto their side into the recovery position so they won’t choke if they throw up. This is especially important if the person’s skin is pale, blue or cold, or if their breathing is irregular or too slow or shallow.


When is using heroin a problem?

Using heroin 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 heroin, but even a single occasion of use can lead to a problem. For instance, if we share needles or straws, we are at risk of infection. 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. This happens when it takes more of the drug to achieve the positive effects. If we develop tolerance to heroin 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 heroin 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 heroin influence their risk of developing problems. For instance, if a person uses heroin out of curiosity, only occasional social use may follow. But when a person uses heroin to cope with a long-term problem such as trauma, then more long-lasting and intense use may follow.

People who develop a dependence on heroin 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 heroin. Because symptoms can be strong and unpleasant, some people continue using the drug even when they don’t want to.

Mixing heroin with other substances

People sometimes mix heroin with other substances to experience different feelings or to offset the effects. For instance, a person may use heroin to help them relax and rest after using cocaine, or use cocaine to reduce the negative effects of withdrawal from heroin. 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 heroin is itself a depressant, using heroin with other depressants can intensify these effects and increase our chance of overdose or death.


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


Combining cannabis with heroin 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.


When prescription or over-the-counter medications are used with heroin, 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 heroin

Whenever we decide to use heroin, 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 heroin 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. Limiting how much we use in a given period helps us carefully monitor our use and reduce the risk of overdose.

Tip: Buy less so you use less, and set a limit on how much you will use at one time. Start with a small amount whenever you get a new supply.

Not too often. Limiting how often we use helps decrease the risk of dependence and reduce harms to ourselves and others over time.

Tip: Reflect on your pattern of use and identify the situations in which you are likely to use. And then try to break the pattern by consciously planning other activities for those situations.

Only in safe contexts. Trusting and feeling safe in your surroundings can make injecting or snorting easier and therefore safer.

Tip: Use with a buddy. Using alone means no one will be there to help you if you overdose.


Legal status

Heroin is a controlled substance in Canada. It is illegal to produce, sell, import, export or use the drug. Under current laws, offenders may receive a fine, a prison term and a criminal record that could affect their future employment, travel plans and educational opportunities.


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

To better understand how substances play a role in your life, visit the You and Substance Use Workbook. 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 website: www.cisur.ca.


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 Addictions 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 www.cisur.ca.