About opioids

Learn about opioids, their side effects and how to use them more safely.

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About opioids

Opioids are drugs with pain relieving properties that are used primarily to treat pain.

Opioids can also induce euphoria (feeling high), which gives them the potential to be used improperly.

Opioids can be prescribed medications:

  • codeine
  • fentanyl
  • morphine
  • oxycodone
  • hydromorphone
  • medical heroin

Opioids can also be produced or obtained illegally.

Opioid medications

Opioids are intended to treat pain.

Doctors may also sometimes prescribe them for other conditions, such as:

  • acute (short-term) moderate to severe pain
  • chronic (long-term) pain
  • moderate to severe diarrhea
  • moderate to severe cough

Prescription opioid medications are available in various forms, such as:

  • syrups
  • tablets
  • capsules
  • nasal sprays
  • skin patches
  • suppositories
  • liquids for injection

If you have been prescribed an opioid medicine, it should:

  • only be taken as prescribed
  • never be used by someone for whom it was not prescribed
  • never be taken with alcohol or other medications (except as prescribed)

Keep your medication safe to help prevent problematic use by others by:

  • never sharing your medication with anyone else
  • this is illegal and may also cause serious harm or death to the other person
  • keeping track of the amount of pills remaining in a package
  • storing opioids in a safe and secure place, out of the reach of children and teenagers

Unused portions of opioid medicine should always be:

  • kept out of sight and reach of children and pets
  • stored in a safe place to prevent theft, problematic use or accidental exposure
  • returned to a pharmacy for safe disposal if it is no longer needed or expired
  • this prevents any possibility of illegal use and protects the environment from contamination

Short-term effects of opioids

The short-term side effects of using opioids may include:

  • drowsiness
  • constipation
  • impotence in men
  • nausea and vomiting
  • euphoria (feeling high)
  • difficulty breathing, which can lead to or worsen sleep apnea
  • headaches, dizziness and confusion, which can lead to falls and fractures

Long-term effects of opioids

The longer-term side effects of using opioids may include:

  • increased tolerance
  • substance use disorder or dependence
  • liver damage
  • infertility in women
  • worsening pain (known as "opioid-induced hyperalgesia")
  • life-threatening withdrawal symptoms in babies born to mothers taking opioids

Even when prescribed to treat a specific condition or pain, there are serious side effects and risks of using opioids, including:

  • physical dependence
  • substance use disorder
  • overdose

If you have been taking opioids for a period of time, your body becomes accustomed to or tolerant of that opioid dose. You may require increasing amounts of the opioid to get the same effect. If you stop taking the drug for a few days and then start taking the drug at the same dose you were used to, it may increase chances of an overdose. This is because you lose tolerance to the medication when stopping it, even for a few days.

You are likely to experience withdrawal symptoms when you lower your opioid dose quickly or you suddenly stop taking it. If you plan to reduce your dose, do it with help from a health care provider.

Problematic opioid use

Opioids have the potential for problematic use because they can produce euphoria (feeling high).

When people think about problematic opioid use, they often think about when someone takes an illegally produced or obtained opioid, such as:

  • heroin
  • fentanyl

Problematic use of opioids also includes when you:

  • use an opioid medicine improperly, such as:
    • taking more than is prescribed
    • taking it at the wrong time
  • use an opioid medicine that was not prescribed for you

Substance use disorder

When someone is affected by substance use disorder, or addiction, they crave the drug and continue using it despite the harmful effects. The drug becomes the focus of their feelings, thoughts and activities.

Opioid use disorder also changes the brain and the body in ways that can make it hard to stop using. This is because the body gets used to a regular supply of the drug. If you stop using the drug, or lower your dose quickly, you will likely experience withdrawal symptoms.

Physical withdrawal effects may include:

  • chills
  • diarrhea
  • insomnia
  • sweating
  • body aches
  • nervousness
  • widespread or increased pain
  • irritability and agitation
  • nausea and stomach pain

The severity of withdrawal and how long it lasts depend on:

  • how much drug was taken
  • which opioid was used
  • how long the drug was used

Substance use disorder treatment may include:

  • counselling and support
  • detoxification (managing withdrawal)
  • medication-assisted treatment

Medication-assisted treatment involves taking a prescribed opioid medication such as:

  • methadone
  • buprenorphine/naloxone (Suboxone® and its generic forms)

Help for substance use disorder

Help is available whether you need it for yourself, a friend or a family member. You can also contact your health care provider for help with substance use disorder.


An overdose can happen when you take too much of an opioid. Opioids affect the part of your brain that controls your breathing. When you take more opioids than your body can handle, your breathing slows. This can lead to unconsciousness and even death.

You are at risk of an overdose if you take:

  • an opioid not prescribed for you
  • a higher opioid dose than prescribed for you
  • illegally produced or obtained drugs that may contain opioids
  • an opioid with alcohol
  • an opioid with other depressant drugs including:
    • sleeping pills (benzodiazepines)
    • anxiety medication
    • muscle relaxants

Learn more about opioid overdose.

Other health risks of using opioids


Some people inject opioids with a needle.

If you share needles with others you have a higher chance of getting infected with viruses like the human immunodeficiency virus (HIV) or hepatitis C.

You can permanently harm your veins and organs by injecting drugs.


There is an increased risk of premature delivery for women who use opioids regularly, including prescription opioids. There is also a risk the baby may be born with life-threatening withdrawal symptoms.

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