If used as prescribed and recommended, fentanyl is an effective medication. However, there are risks associated with both use and misuse.

Regular use of fentanyl may cause:

• Mood instability
• Reduced libido
• Constipation
• Menstrual problems
• Respiratory impairment
• If injected, a higher risk of overdose and infection.

As fentanyl is such a potent opioid, there is a serious risk that non-medical use may result in overdose.

The signs of overdose include:

• Extreme drowsiness or the person may even be impossible to wake (‘on the nod’)
• Unresponsive to verbal approach
• Small or ‘pinned’ pupils
• Slowed breathing and heart rate (down to four breaths per minute)
• Total respiratory failure
• Snoring
• Blue or purple coloured skin (cyanosis), usually starting on lips and fingers
• Low blood pressure
• A drop of body temperature to below 35°C (hypothermia).

If caught in time, the effects of overdose can be reversed by the administration of naloxone. When medications are used outside the guidelines for safe and effective use, adverse effects may be more likely.

In 2022, 240 overdose deaths were recorded related to the use of synthetic opioids such as fentanyl, tramadol and pethidine.

The effects of taking fentanyl with other drugs, including over the counter or prescription medications, can be unpredictable and dangerous.

For instance, it can increase the risk of adverse effects and respiratory depression if taken with alcohol. Fentanyl mixed with benzodiazepines may increase the sedative effects of both drugs and also increase the risk of respiratory depression, while mixing it with antidepressants may result in severe, unpredictable reactions.

Fentanyl is a powerful opioid, and opioids have the highest dependence liability of all illicit drug classes. This may be a problem if the drug is used over a long period of time.

Usually, withdrawal begins between eight and 12 hours after the last dose.

Withdrawal symptoms may include:

• Uneasiness/anxiety
• Yawning
• Diarrhoea
• Stomach cramps
• Runny nose
• Sleeping difficulties
• Joint pain.

These symptoms generally reach their peak on the third day following cessation.

Other harmful use practices that may lead to dependence include:

• Excess prescriptions
• Long-term use (more than three months)
• Rapid dose escalations
• Extra-medical use
• Use with other drugs, such as tricyclic antidepressants, antipsychotics and pregabalin.

Rates of psychopathology amongst people who use opioids for non-medical use are extremely high. Affective disorders are prominent with lifetime rates of severe depression, dysthymia and anxiety disorders.

Treatment for fentanyl dependence differs depending on severity of the addiction, and a range of other factors.

Some treatments include taking opioid agonist or antagonist drugs like buprenorphine, naltrexone or methadone. This pharmacotherapy helps stabilise people with an opioid dependence and reduce harms related to drug use.

Other treatments include behavioural therapy in an inpatient or outpatient setting, cognitive behavioural therapy, specialised treatment programs, and recovery groups.

According to the Australian Institute of Health and Welfare’s National Drug Strategy Household survey, 2.6 million (or 11.9%) people in Australia reported non-medical use of a pharmaceutical drug at some point in their lifetime.

In 2022-23, 5.9% of people aged 14 and over who used painkillers/pain relievers and opioids for non-medical purposes in the previous 12 months, reported using fentanyl.

The Illicit Drug Reporting System (IDRS) is an Australian monitoring system run by the National Drug and Alcohol Research Centre (NDARC) at UNSW Sydney that identifies emerging trends of local and national concern in illicit drug markets.

The Ecstasy and Related Drugs Reporting System (EDRS) is an Australian monitoring system run by NDARC that identifies emerging trends of local and national interest in ecstasy and related drug use, markets and harms.

The Pocket Guide to Drugs and Health is a publication authored by experts from NDARC that provides information for health professionals on the impact of drug use.

The Australian Institute of Health and Welfare collects information on alcohol and tobacco consumption, and illicit drug use among the general population in Australia.

The Australian Bureau of Statistics is Australia’s national statistical agency, providing official statistics on a range of economic, social, population and environmental matters of importance to Australia.

Alcohol and Drug Foundation (2024). Fentanyl. Retrieved from: adf.org.au/drug-facts/fentanyl/

Australian Institute of Health and Welfare (2024). National Drug Strategy Household Survey 2022–2023. AIHW, Australian Government. Retrieved from: aihw.gov.au/reports/illicit-use-of-drugs/national-drug-strategy-household-survey/data

Darke S., Lappin, J., & Farrell M. (2024). The Clinician’s Guide to Illicit Drugs and Health (Revised Edition). London: Silverback Publishing.

Chrzanowska, A., Man, N., Sutherland, R., et al (2024). Trends in overdose and other drug-induced deaths in Australia, 2003-2022. Sydney: National Drug and Alcohol Research Centre, UNSW Sydney. Retrieved from: unsw.edu.au/research/ndarc/resources/trends-drug-induced-deaths-australia-2003-2022