Last published: November 05, 2021

What are opioids?

Opioids include any drug that acts on opioid receptors in the brain, and any natural or synthetic drugs derived from or related to the opium poppy. Opiates are a subset of opioids, which are naturally derived from the opium poppy plant, rather than synthetic substances.1

The opioid receptor system

Opioids bind to opioid receptors which depress the central nervous system, and slow down messages travelling between the brain and body. This slows down breathing and heart rate. Opioid receptors also stimulate the release of dopamine, which leads to sensations of pleasure and pain relief.1

If a person’s breathing and heart rate slow down to a certain point, they may stop breathing, and an overdose can occur.1 Opioid overdose can result in death and other injuries but can be reversed by CPR and naloxone administration.2

Naloxone also binds to opioid receptors but has the opposite effect than other opioids. It blocks the receptors from attaching to other opioids, and acts to reverse an overdose.

Naloxone has been used in Australia for several years in clinical and ambulance settings and is now available over-the-counter.

How are they used?

Opioids can be used in various ways – opioid-based medications are usually in tablet form and are often swallowed. Opioid-substitution treatment, which is in liquid, tablet and film formations, is used orally. Film formations are dissolved under the tongue. Heroin is usually injected but is also snorted or smoked.

Explore opioids on the Drug Wheel

Drug wheel segment - Opioids segment@2x.png

Types of commonly used opioids


Opioids include certain types of pain killers, known as ‘opioid pain medications’ and illegal drugs, such as heroin. Some opioids are plant-based and come from the opium poppy (opiates), whilst others are synthetic or ‘man-made’.

Common types of opioid include codeine (Panadeine®, Panadeine Forte® and Nurofen Plus®), fentanyl, morphine, oxycodone (Endone® or OxyContin®), buprenorphine (Subutex® or Suboxone®), methadone (Methadone Syrup® and Biodone Forte®), tramadol and heroin.

Newer psychoactive opioid substances include: U-47700, AH-7921, O-desmethyltramadol, MT-45, acetylfentanyl and furanyl-fentanyl.

Opioid-based medications

Common types of opioid-based medications include codeine (Panadeine®, Panadeine Forte® and Nurofen Plus®), fentanyl, morphine, oxycodone (Endone® or OxyContin®), buprenorphine (Subutex® or Suboxone®), methadone and tramadol.

They produce feelings of pain relief in the same way as other opioids such as heroin. Opioid-based medications are commonly prescribed by doctors, and until 2018, some lower strength opioids could be bought over the counter. However opioid-based medications are now only available with a prescription.

Many people don’t realise that many medications prescribed for pain relief can cause dependence. If they are overused or combined with other drugs that depress the central nervous system, such as alcohol or benzodiazepines, they may also cause overdose.  Pharmaceutical opioids now account for more drug-related deaths in Australia than any other drug category.3


Heroin is the common name for diecetylemorphine or diamorphine. Diamorphine is used in clinical settings and is the substance used in prescription heroin programs internationally. Heroin is an opiate, meaning it is a naturally occurring substance of the opium poppy.4

Opiate substitution treatments

Methadone (Methadone Syrup® and Biodone Forte®) and buprenorphine (Suboxone® or Subutex®) are opioid-based medications used to treat addiction to heroin or other opioids, also known as pharmacotherapy or opiate substitution treatment (OST).

OST is prescribed by a doctor to assist people using opioids to reduce or stop their use. They are used to manage cravings and withdrawal symptoms. Methadone is also used in clinical settings following heart attacks, trauma and surgery.


Naloxone is classified as an opioid as it binds to opioid receptors, however it acts in the opposite way of most opioids. Naloxone blocks other opioids from binding to receptors and can reverse opioid overdoses within minutes. It doesn’t have the same effect as other opioids and doesn’t produce feelings of pain relief and pleasure.

Naloxone is only useful to reverse overdoses of other opioids, and will not affect overdoses due to alcohol, benzodiazepines, stimulant or hallucinogenic drugs, or any other non-opioid based medications.

Effects of opioids

There is no safe level of drug use. Use of any drug always carries some risk. It’s important to be careful when taking any type of drug.

Opioids affect everyone differently, based on:

  • the person’s size, weight and health
  • whether the person is used to taking it
  • whether other drugs are taken around the same time
  • the amount taken
  • the strength of the drug.

Generally, people who use opioids may experience the following:

  • extreme relaxation
  • drowsiness and clumsiness
  • confusion, slurred speech,
  • slow breathing and heartbeat.

If a large dose is consumed, someone may develop:

  • cold, clammy skin
  • slow breathing
  • blue lips and fingertips
  • falling asleep (‘going on the nod’)
  • death by respiratory depression.

Long-term effects include:

  • increased tolerance
  • constipation
  • dependence
  • damage to vital organs such as the lungs, brain and heart.4

Using opioids with other drugs

The effects of taking opioids with other drugs – including over-the-counter or prescribed medications – can be unpredictable and dangerous, and could cause:
Opioids + alcohol, cannabis or benzodiazepines: slow down breathing and brain activity, and increased risk of overdose.
Opioids + ice, speed or ecstasy: enormous strain on the heart and kidneys, and increased risk of overdose.5

More on Polydrug use

‘Polydrug use’ is a term for the use of more than one drug or type of drug at the same time or one after another.1 Polydrug use can involve both illicit drugs and legal substances, such as alcohol and medications.

Health and safety

Use of opioids is likely to be more dangerous when:

  • combined with alcohol or other drugs, in particular benzodiazepines or other opioids, as these can slow breathing and increase the risk of overdose6
  • driving or operating machinery, as a person’s ability to judge distance and space is extremely limited
  • a person is alone (in case medical assistance is required). It’s recommended that an unaffected person is present incase assistance is required
  • injecting equipment is not sterile.7

If you or someone you know is using opioids, it would be a good idea to talk with your doctor about accessing naloxone, the drug that reverses opioid overdoses. Your friends or family members can be trained in overdose reversal in case of an emergency.

Find out more about overdose.

Pain management plans

If you’re prescribed opioid-based medications, ask your doctor about a ‘pain management plan’, and other non-medicine (such as physical therapy) and non-opioid strategies (such as paracetamol) you can use to complement your treatment and reduce your reliance on opioid-based medications.

Tolerance and dependence

After prolonged use, many drugs can cause dependence. People who use a drug regularly can develop dependence and tolerance to it. This means they need to take larger amounts of the drug to get the same effect.

Dependence on a drug can be psychological, physical, or both. People who are dependent on a drug find that using it becomes far more important than other activities in their life. They crave the drug and find it very difficult to stop using.

People who are psychologically dependent on a drug may feel the urge to use it when they are in specific surroundings, such as socialising with friends.

Physical dependence occurs when a person’s body adapts to a drug and gets used to functioning with the drug present.

Getting help

If your use of opioids is affecting your health, family, relationships, work, school, financial or other life situations, or you’re concerned about a loved one, you can find help and support.


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  1. Penington Institute. (2018). The COPE Program: Overdose fact sheet
  2. Penington Institute. (2018). The COPE Program: Naloxone fact sheet
  3. Penington Institute. (2018). Australia’s Annual Overdose Report 2018
  4. National Drug and Alcohol Research Centre. (2016). Heroin fact sheet
  5. Goldsmith, R., Weisz, M. & Shapiro, H. (2010). The Essential Guide to Drugs and Alcohol. (14th ed.). London: DrugScope.
  6. Queensland Network of Alcohol and other Drugs Agencies. (2018). Opioids and benzodiazepines
  7. NPS MedicineWise 2016. How to use opioid medicines safely