Cannabis remained Europe’s most commonly used drug in 2025, according to new wastewater analysis from the European Union Drugs Agency (EUDA), suggesting around 8.4% of European adults have consumed cannabis within the last year.
Since 2011, the EUDA has monitored the wastewater of municipal locations across Europe to estimate community consumption of various illicit drugs.
The programme, coordinated by the Sewage analysis CORe group Europe (SCORE), a network established to standardise wastewater-based drug monitoring across the region, now analyses data from 115 cities across 25 countries to help illustrate shifts in drug use patterns across the region.
Its latest dataset is based on samples collected between March and May 2025, shows that while overall levels of cannabis metabolites did not change year-on-year, individual cities recorded mixed trajectories, highlighting shifting local dynamics.
Flat headline figures mask local changes
At a headline level, cannabis use across Europe appeared to remain flat in 2025 year-on-year. Wastewater analysis, which estimates consumption by measuring drug residues in sewage, found no overall increase or decrease in THC-COOH, the primary metabolite used to track cannabis use.
Despite this, analysis of the 63 cities with comparable data from 2024 found that 21 cities, or 33%, reported increases in cannabis metabolite loads, while 28 cities, or 44%, recorded declines, and 14 cities, or 22%, remained stable.
This uneven distribution suggests that significant changes were happening at the local level in either direction, which may reflect a shift in policy, supply chains, pricing, or consumer behaviour.
Geographically, cannabis use continues to be concentrated in western and central Europe. The highest levels of THC-COOH were detected in cities in the Netherlands, Germany, and Slovenia.
While the report does not directly assess regulatory frameworks, the concentration of use in these markets coincides with more developed cannabis policy environments.
As seen in the above map, dense clusters of elevated cannabis metabolite loads appear across these regions, with comparatively lower levels observed in much of eastern Europe. This pattern has remained consistent across multiple years of monitoring, suggesting entrenched regional differences in cannabis demand.
In a global context, the study indicates that even the highest cannabis consumption levels recorded in European cities remain below those observed in North America, particularly in Canada and the United States.
More even usage compared to other drugs
Unlike stimulants such as cocaine or MDMA, which show pronounced weekend spikes linked to nightlife and recreational settings, cannabis use appears more evenly distributed throughout the week.
Wastewater data indicate relatively consistent levels of THC-COOH from weekdays through weekends in many cities, suggesting that cannabis consumption is less episodic and more habitual in nature. This aligns with broader survey data indicating a wider and more regular user base compared to other illicit substances.
Wastewater-based epidemiology has become an increasingly important tool for monitoring drug use, offering near real-time insights into consumption patterns across large populations. The method involves analysing untreated sewage to detect drug residues and estimate usage levels per 1,000 inhabitants.
However, the approach has limitations. It cannot determine how many individuals are using cannabis, how frequently they consume it, or the potency of products in circulation. In addition, THC-COOH is excreted in relatively low quantities, meaning further research is needed to refine measurement accuracy.
As a result, wastewater data is best understood as a directional indicator of total consumption rather than a precise measure of prevalence.
Cannabis remains Europe’s most widely used illicit drug, with an estimated 24 million adults, or 8.4% of those aged 15 to 64, reporting use in the past year. Yet both survey data and wastewater analysis point to increasingly divergent patterns of cannabis use across European markets.
As regulatory approaches continue to evolve, particularly in key markets such as Germany and the Netherlands, the divergence seen at the city level may become an increasingly important signal for policymakers and industry operators alike, offering early insight into how legal and quasi-legal frameworks are reshaping consumption patterns on the ground.
