Indicators of substance use disorder include behavioral and functional patterns such as using more of a substance than intended, difficulty controlling use, and continuing use despite significant adverse consequences. Dependence-related features may include tolerance, withdrawal, and psychological dependence or drug craving. Possible observable signs include changes in weight, appetite, sleep, pupil size, eye appearance, speech, coordination, tremors, nasal symptoms, or grooming; these signs should be considered within the broader pattern of substance use.