Polysubstance Use Among the Homeless in Germany: A Nationwide, Cross-Sectional Multicenter Study.

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 PEH is largely lacking. In this study, we estimate the prevalence of substance use among PEH and identify subgroups at risk of polysubstance use.

Methods: A cross-sectional study of 674 PEH was conducted in four German metropolitan areas in 2021. All PEH 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 PEH had no recent substance use (95% confidence interval [31;39], while 34% had recently engaged in polysubstance use ([30;38]). Alcohol was the most prevalent substance (39% [35;43]), followed by CNS stimulants (30% [27;34]), cannabis (28% [24;32]), and narcotic analgesics (18% [15;21]). Polysubstance use was linked to younger age, prior incarceration, current tobacco use, and geographical location.

Conclusion: In Germany today, the number of PEH 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.