Comorbidity describes two or greater issues or illnesses occurring in the equal person. They can arise at the equal time or one after the other. Comorbidity also implies interactions between the illnesses that can worsen the path of both. Many people who have a substance use ailment also increase different mental illnesses, simply as many those who are diagnosed with mental infection are often recognized with a substance use ailment. For example, about half of individuals who enjoy a mental contamination will also experience a substance use disease at some point in their lives and vice versa. Few research have been carried out on comorbidity in children, but those which have been conducted recommend that teenagers with substance use problems additionally have excessive charges of co-happening mental contamination, including depression and anxiety. Comorbidity is described because the co-occurence of more than one sickness in the same individual. In its broadest sense, comorbidity can consist of the co-incidence of medical and psychiatric issues, inclusive of the dementia associated with organic situations or the affective changes resulting from endocrinopathies. In psychiatry, comorbidity is usually taken to intend the association of diagnosable psychiatric disorders. Comorbidity is an epidemiologic phenomenon, referring to the characteristics of a population, and the suggested comorbidity of sure disorders in a population does now not always imply that they may be comorbid in any given character. However, observations of comorbidity among populations may be extremely useful in informing the therapist's expertise of an character patient. Comorbidity is associated with worse fitness outcomes, greater complex clinical management, and increased fitness care costs. There isn't any agreement, however, on the which means of the term, and associated constructs, inclusive of multimorbidity, morbidity burden, and patient complexity, aren't well conceptualized. In this article, we evaluate definitions of comorbidity and their relationship to related constructs.