The effects of a drug refer to the changes or alterations that occur in an individual's physical, mental and emotional state after consuming it. These can include both desired and undesired outcomes such as feelings of euphoria, increased energy levels, heightened sensory perception, changes in mood or behavior, and potential side effects like drowsiness, nausea, or anxiety. The specific effects of a drug depend on various factors including the individual's physiology, the dosage taken, and any pre-existing medical conditions.