Clinical trials and studies have assessed ketamine as a treatment for depression. Currently, ketamine (esketamine hydrochloride) in the form of a nasal spray is available for treatment-resistant depression in Australia.

There have been deaths associated with ketamine overdose, but they have been predominantly attributed to polydrug use. Signs of overdose include:

• Fast heart rate (tachycardia)
• Hyperthermia
• Nausea
• Blurred vision
• Tremors
• Confusion
• Delusions
• Anxiety
• Severe agitation.

The effects of using ketamine with other drugs, including over-the-counter or prescription medications, is highly unpredictable.

The use of ketamine with psychostimulants (e.g., amphetamine, ecstasy and methamphetamine) can put enormous strain on the heart, increasing the risk of a cardiovascular event.

The toxic effect of ketamine use is a psychosis-like state, sometimes referred to as a ‘k hole’.

There is an established ketamine dependence and withdrawal syndrome. Withdrawal symptoms usually last between four and six days. These include:

• Anxiety
• Sweating
• Heart palpitations
• Cravings for ketamine
• No appetite
• Tiredness
• Restlessness
• Tremors.

Hallucinogens can give rise to psychotic symptoms, sometimes known as a ‘bad trip’. It has been found that following a single dose, healthy volunteers can experience both positive and negative psychotic symptoms.

Daily users of ketamine experience psychotic symptoms, especially among people who have a history of mental illness, including:

• Delusions
• Dissociation
• Anxiety or panic attacks
• Psychotic symptoms, which can be triggered in some people (e.g., those with schizophrenia).

There is a lack of research on the treatment of hallucinogen dependence. Some treatments for other drugs like psychostimulants may be appropriate. The effectiveness for cognitive behavioural therapy for the treatment of psychostimulant and cannabis dependence suggests that it might be useful for ketamine dependence.

According to the Australian Institute of Health and Welfare’s National Drug Strategy Household Survey, use of ketamine in the previous 12 months increased from 0.9% in 2019 to 1.4% in 2022-2023.

The increase in recent use was largely driven by people in their 30s, from 0.5% in 2019 to 2.5% in 2022–‍2023. However, it was people in their 20s who were most likely to have used ketamine in the previous 12 months, with 4.2% having done so.

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). Ketamine. Retrieved from: adf.org.au/drug-facts/ketamine/

Australian Institute of Health and Welfare (2024). Low-prevalence illicit drugs in the NDSHS, AIHW, Australian Government. Retrieved from: aihw.gov.au/reports/illicit-use-of-drugs/low-prevalence-illicit-drugs-ndshs

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

Zarate, Carlos A., and Mark J. Niciu (2015). “Ketamine for Depression: Evidence, Challenges and Promise.” World Psychiatry, vol. 14, no. 3, pp. 348–50. Retrieved from: doi.org/10.1002/wps.20269