Drug effects refer to the changes that occur in the body and mind after consuming a substance. These effects can vary widely depending on the type of drug, the dosage, and the individual's unique biology. Common effects include alterations in mood, perception, and behavior, as well as physical changes like increased heart rate or drowsiness. Different categories of drugs, such as stimulants, depressants, and hallucinogens, produce distinct effects. For example, stimulants like caffeine can increase alertness, while depressants like alcohol may lead to relaxation. Understanding these effects is crucial for making informed decisions about drug use.