Polysubstance Use Among the Homeless In Germany
A nationwide, cross-sectional multicenter study
Original article
Summary
In a nationwide cross-sectional study, researchers at the University Medical Center Hamburg-Eppendorf (UKE) investigated substance use among homeless people in Germany.
The researchers used a comprehensive drug screening (LC/MS-MS). They observed a tripartite distribution within the cohort:
- approximately 35% of the individuals examined had not consumed any substances in the previous 24 to 48 hours,
- around one-third had consumed one substance group, and
- about 34% had taken several substances from different substance groups.
The most common substances, in descending order, were alcohol, central nervous system stimulants (including amphetamines, cocaine, and ecstasy), cannabis, and narcotic analgesics (such as heroin, morphine, methadone, and fentanyl).
According to the study, young, homeless people who smoked and had a criminal record were particularly likely to use multiple substances concurrently.
Background
Although substance use is known to be an integral factor in homelessness and the continuation of homelessness, little research into substance consumption in this vulnerable sector of the population has been conducted.
Given the lack of a systematic review on the prevalence of substance use among people experiencing homelessness, the researchers reviewed the literature and found only three population-based studies on people experiencing homelessness from different parts of France, Spain, and Canada.
In all three countries, people experiencing homelessness were recruited from three major cities, with settings classified as roofless and houseless according to the European Typology on Homelessness and Housing Exclusion (ETHOS).
The Canadian study also included people experiencing homelessness from inadequate settings, as defined by ETHOS (e.g., mobile homes or temporary structures). The French study stated the prevalence of tobacco, alcohol, and cannabis use among PEH as 40%, 30%, and 10%, respectively, while the Spanish and Canadian studies documented only the prevalence of “problematic substance use”.
In-depth information on the distribution of illicit substance use was not reported in any of these studies. No previous population-based study determined substance use through toxicological analysis.
In Germany, official figures reported 262,000 people experiencing homelessness in 2022, with 178,000 persons registered in emergency accommodation. Between 2022 and 2024, the number of persons living in such shelters more than doubled to 440,000. Increasing numbers of people experiencing homelessness have also been observed in other European countries, such as Ireland.
Furthermore, mortality as a direct consequence of illicit substance use in Germany has almost doubled in the past decade, reaching 2137 deaths in 2024. Polysubstance use, mainly in the form of heroin or other opioids mixed with other substances, was a common cause of death, suggesting that this is a widespread and hazardous practice.
Meaning and Conclusions
Among 674 people experiencing homelessness from four metropolitan areas in Germany, two thirds had recently used alcohol, cannabis, or illegal substances. One third of the people experiencing homelessness were found to have recently used substances from at least two groups, most commonly alcohol together with CNS stimulants or alcohol and cannabis. Among people experiencing homelessness with documented substance use, polysubstance use appears to be a common practice.
This is the first population-based study to estimate the prevalence of substance use by means of toxicological measurements in a large, heterogeneous sample of people experiencing homelessness.
At first sight, the high prevalence of substance use among people experiencing homelessness is not surprising and corresponds to previous studies. However, the study findings add a critical dimension: a tripartition of people experiencing homelessness into abstainers, single-substance users, and polysubstance users.
Considerable heterogeneity of substance use can be observed among people experiencing homelessness:
- one third did not test positive for any substance,
- while another third tested positive for two or more substances.
Very high blood levels of alcohol and CDT, together with a high proportion of people experiencing homelessness engaging in heavy episodic alcohol use on a daily or weekly basis, indicate severe chronic alcohol use. The high rates of cardiovascular and liver problems observed in this population may be caused by regular alcohol intake over a long period.
Nevertheless, it needs to be stressed that a considerable number of people experiencing homelessness do not use any substances. In fact, the proportion of abstainers may be similar to that in the general population or even larger. In 2021, three out of ten adults in Germany reported that they had not consumed alcohol in the previous month.
With both abstainers and heavy users represented among people experiencing homelessness, shared spaces may be difficult to establish. In most of the facilities surveyed, use of alcohol or illegal substances is not allowed, creating a barrier to heavy users but potentially creating a safe environment for abstainers. By acknowledging the differential needs of people experiencing homelessness, services can be tailored to meet the specific requirements of different subgroups. Essentially, this means housing programs that presuppose recovery from substance use problems; such programs have shown promising health impacts.
A number of studies have revealed that incarceration constitutes a major, partly avoidable risk factor for continued homelessness and health consequences. This study shows, in addition, that previous imprisonment is a strong predictor of current polysubstance use.
- In the study sample, 54% of people experiencing homelessness reported having been imprisoned at some point in their lives.
Imprisonment can result from criminal offenses or non-payment of administrative fines. In Germany, a substitute custodial sentence can be imposed for non-payment of administrative fines (e.g., as a result of not paying transport fares). Such sentences disproportionately affect socioeconomically disadvantaged persons, including people experiencing homelessness and those with substance use problems.
The study findings show that polysubstance use was identified in around one third of people experiencing homelessness – in addition to a multitude of other environmental and social risk factors. Within this already vulnerable population, those engaging in polysubstance use may represent the subgroup at greatest risk, given their elevated rates of incarceration.
Against the backdrop of a growing people experiencing homelessness population, wide availability of legal and illegal substances, and escalating rates of illicit substance overdose deaths in Germany, continued monitoring and targeted support of those in need appear especially warranted.
Abstract
Background
The number of people experiencing homelessness (PEH) in Germany reached 440,000 in 2024, double the total from 2022. Representative data on substance use among people experiencing homelessness is largely lacking.
In this study, the researchers estimate the prevalence of substance use among people experiencing homelessness and identify subgroups at risk of polysubstance use.
Methods
A cross-sectional study of 674 people experiencing homelessness was conducted in four German metropolitan areas in 2021. All people experiencing homelessness were interviewed and provided blood samples in homeless support facilities.
Toxicological analysis of serum samples revealed the presence of 22 substances, which were grouped as alcohol, central nervous system (CNS) stimulants, narcotic analgesics, and cannabis.
Polysubstance use was defined as the detection of substances belonging to at least two of these groups.
Results
The toxicological analyses revealed that 35% of people experiencing homelessness had no recent substance use, while 34% had recently engaged in polysubstance use.
Alcohol was the most prevalent substance (39%), followed by CNS stimulants (30%), cannabis (28%), and narcotic analgesics (18%).
Polysubstance use was linked to younger age, prior incarceration, current tobacco use, and geographical location.
Conclusion
In Germany today, the number of people experiencing homelessness is growing, substance availability is widespread, and drug-related deaths are on the rise. It is, therefore, vitally important to continue monitoring the situation and to provide targeted support to those who need it.