While a substantial body of research has demonstrated the frequent co-occurrence of psychiatric disorders with ADHD, somatic health conditions have been less studied. In this article, we review the current literature on the link between adult ADHD, somatic comorbidities, and lifestyle factors. Somatic conditions that have shown robust association with ADHD include metabolic, nervous system, and respiratory diseases. A limited number of studies have also suggested tentative associations between ADHD and age-related disorders, such as dementia and cardiovascular disease. These associations may, in part, be explained by lifestyle factors, such as unhealthy diet, smoking and substance (drug and alcohol) misuse. These insights highlight the importance of rigorous assessments of somatic conditions in patients with ADHD, and of considering patients' long-term health. It is important that future research identifies risk factors that contribute to this increased risk of somatic health conditions in ADHD, to improve efforts aimed at prevention and treatment of somatic conditions in adults with ADHD.