A groundbreaking study from the University of Adelaide has illuminated a concerning trend in drug consumption patterns across Australia: a significant surge in recreational ketamine use. By analyzing wastewater from treatment plants nationwide, researchers have uncovered evidence of escalating non-medical consumption, particularly pronounced on weekends and in affluent urban areas. This research not only highlights the power of wastewater epidemiology as a tool for public health surveillance but also underscores the pivotal role Australian universities play in tackling emerging substance use challenges through innovative methodologies.

Ketamine, a dissociative anesthetic originally developed for medical and veterinary use, produces effects ranging from pain relief and sedation to profound hallucinations and a sense of detachment from reality. In recent years, its off-label application for treatment-resistant depression—often via esketamine nasal spray—has gained traction. However, the study's findings point to a parallel rise in recreational misuse, where users seek euphoric highs, often in party settings or combined with other substances like MDMA in what's known as "kitty flipping."

The Innovative Approach of Wastewater Epidemiology

Wastewater-based epidemiology represents a paradigm shift in monitoring community-level drug use. Unlike traditional surveys, which rely on self-reporting and can suffer from bias or underreporting due to stigma, this method captures excreted drug metabolites directly from sewage systems. At the University of Adelaide's School of Pharmacy and Biomedical Sciences, Professor Cobus Gerber and his team have pioneered this technique in Australia, partnering with the Queensland Alliance for Environmental Health Sciences and supported by the Australian Criminal Intelligence Commission.

The study examined daily influent samples from up to 50 wastewater treatment plants (WWTPs) across capital cities and regional sites in every state and territory. Spanning December 2020 to April 2025, the dataset covered approximately 53 percent of Australia's population. Samples underwent solid-phase extraction and liquid chromatography tandem mass spectrometry to quantify norketamine—a primary ketamine metabolite—normalizing results to mg/day per 1,000 people for accurate population estimates. This rigorous process allows for real-time insights into consumption trends without invading individual privacy.

National Trends: A 2.2-Fold Increase in Ketamine Loads

From 2022 onward, norketamine mass loads showed a marked uptick, rising from a low of about 1.6 mg/day/1,000 people to 5.8 mg/day/1,000 by late 2025—a roughly 2.2-fold increase nationally. Early data aligned with expected pharmaceutical prescriptions, but post-2022 patterns diverged sharply, signaling non-prescribed sources. Capital city sites consistently reported higher levels than regional ones, with major urban centers like Adelaide, Sydney, and Melbourne exhibiting the most pronounced elevations.

This trajectory mirrors broader national surveys, such as the National Drug Strategy Household Survey, where lifetime ketamine use climbed from 1.9 percent in 2016 to 4.3 percent in 2023. The wastewater data provides objective corroboration, revealing not just volume but spatiotemporal variations that self-reports often miss.

Weekend Spikes: Hallmarks of Recreational Use

One of the study's most striking revelations was the weekend surge in ketamine excretion—up to 16 times higher than weekdays in select sites. This rhythmic pattern strongly suggests recreational rather than medical consumption, as therapeutic dosing remains steady throughout the week. In high-socioeconomic urban locales, Friday through Sunday loads dwarfed midweek figures, painting a picture of party-fueled usage.

Such oscillations align with global patterns observed in Europe's SCORE program and the U.S. Wastewater Drug Monitoring Project, where dissociatives like ketamine peak during social events. In Australia, this could reflect nightclub scenes, festivals, or private gatherings where ketamine's rapid-onset dissociation enhances experiences.

Socioeconomic and Geographic Disparities

Higher socioeconomic status (SES) sites showed the steepest rises, challenging assumptions that drug use is confined to disadvantaged groups. Affluent suburbs and inner-city precincts near universities and nightlife hubs correlated with elevated loads, possibly linked to disposable income enabling access to diverted pharmaceuticals or imports.

Regionally, while cities dominated, non-metropolitan increases were notable, hinting at spreading trends beyond urban cores. Adelaide, home to the lead researchers, emerged as a hotspot, consistent with prior National Wastewater Drug Monitoring Program (NWDMP) reports flagging South Australia for high dissociative detections.

Health Risks Posed by Escalating Recreational Ketamine

Beyond its allure, recreational ketamine carries substantial risks. Acute effects include dissociation, impaired coordination, and respiratory depression, heightening accident probabilities—especially when mixed with alcohol or stimulants. Chronic users face "ketamine bladder syndrome," or ketamine-induced cystitis, characterized by severe pelvic pain, frequent urination, and potential kidney damage requiring surgical intervention.

Cognitive deficits, memory loss, and mood disorders persist post-use, with animal models and human imaging studies from Monash University revealing structural brain changes akin to schizophrenia. Cardiovascular strain, hypertension, and overdose fatalities—often from poly-drug interactions—have risen internationally, per UNODC data. Australian Poison Information Centres report ketamine-related calls doubling since 2020, underscoring an emerging crisis.

Alcohol and Drug Foundation's ketamine factsheet details these hazards, emphasizing hydration and dosage awareness as harm reduction basics.

Therapeutic Promise Versus Recreational Peril

Ketamine's resurgence owes partly to its psychiatric efficacy. Esketamine (Spravato), approved by the TGA in 2020, offers rapid antidepressant relief for treatment-resistant depression via NMDA receptor antagonism, promoting neuroplasticity. University of New South Wales trials affirm its safety under medical supervision, contrasting starkly with street variants' impurities and overdosing risks.

However, therapeutic hype may normalize self-medication, blurring lines. Wastewater spikes post-2022 coincide with expanded prescriptions and media coverage, suggesting diversion. Universities like UNSW and UQ advocate regulated access while researching misuse prevention.

Context Within Australia's Broader Drug Landscape

The University of Adelaide findings dovetail with NWDMP Report 24 (2025), noting ketamine's record highs amid stable methamphetamine and declining cocaine. Cannabis remains dominant, but dissociatives like ketamine signal shifting preferences toward shorter-acting, introspective highs.

Poly-substance trends worry experts: "kitty flipping" amplifies serotonin surges, risking serotonin syndrome. Festival testing pilots by Harm Reduction Victoria detect adulterated ketamine, informing policy.

ACIC's NWDMP Report 24 charts these evolutions, crediting uni-led analytics.

University of Adelaide's Leadership in Public Health Surveillance

The Australian Centre for Research on Health in Vulnerable Populations at Adelaide University exemplifies higher education's vanguard role. Prof. Gerber's team integrates pharmacology, analytics, and epidemiology, training postgrads in cutting-edge techniques. Collaborations with UQ's Queensland Alliance yield national datasets, influencing policy via Preventative Health SA.

This work extends prior Adelaide studies on methamphetamine hotspots, evolving wastewater science from proof-of-concept to routine surveillance. Funded by NHMRC grants, it equips unis to address social determinants of health proactively.

Implications for Policy, Education, and Harm Reduction

Findings urge targeted interventions: campus awareness campaigns, festival pill-testing expansion, and prescription monitoring. Universities, as youth hubs, can lead via peer education—Monash's Drug Aware integrates wastewater insights into curricula.

Harm reduction prioritizes hydration, avoiding mixes, and recognizing overdose signs (unconsciousness, slowed breathing). Telehealth counseling via Headspace addresses self-medication for mental health.

Photo by Thomas Hoang on Unsplash

Future Directions: Enhancing Wastewater Insights

Ongoing monitoring promises granular data on polysubstance trends and novel synthetics. Integrating AI for metabolite prediction, per UQ prototypes, could forecast outbreaks. Longitudinal studies linking wastewater to hospital admissions will quantify impacts.

Universities must scale capacity, fostering interdisciplinary PhD programs. International exchanges with Europe's SCORE refine methodologies, positioning Australia as a wastewater epidemiology leader.

This University of Adelaide study not only spotlights rising recreational ketamine but catalyzes evidence-based responses, safeguarding communities through academic innovation.