Background: Physical comorbidities and substance use are commonly reported in patients with mental disorders.

Aim: To examine somatic comorbidity in patients with substance use disorders (SUD) compared to patients with mental disorders but no SUD.

Methods: Lifetime prevalence data on mental and physical health status were collected from inpatients in 12 mental health care facilities in five different countries. Differences in somatic comorbidity were examined by means of logistic regression analysis controlling for age and gender.

Results: Of 2,338 patients, 447 (19%) had a primary or secondary SUD diagnosis. In comparison to patients with other mental disorders, patients with SUD had a higher prevalence of infectious and digestive diseases but a lower prevalence of endocrine, nutritional and metabolic disorders. Patterns of physical comorbidities differed according to type of substance used (alcohol use – cardiovascular; tobacco use – respiratory, neoplasms; cannabinoid use – injuries; opioid use – infectious, digestive; benzodiazepine use – endocrine, nutritional, metabolic; stimulants – urogenital).

Conclusions: SUD are related to specific somatic health risks while some of our findings point to potentially protective effects. The widespread prescription of benzodiazepines requires research on physical health effects. Early detection of SUD and their integration into programmes targeting physical comorbidity should be a priority in organizing mental health care.