Symptoms of stimulant-related disorders can vary based on the severity and duration of use but commonly include increased energy, elevated mood, decreased appetite, and heightened alertness during use. Upon cessation or overdose, individuals may experience symptoms such as fatigue, depression, irritability, and intense cravings. Physical signs may also appear, including weight loss, dilated pupils, and cardiovascular changes, highlighting the profound impact of stimulants on both mental and physical health.