A stimulant drug is a substance that increases activity in the central nervous system, which results in an increase in alertness, energy, and attention. Some common synonyms for stimulant drugs include psychostimulants, uppers, energizers, and performance enhancers. Some other less-common synonyms may include speed, pep pills, and wakefulness agents. While these substances can be helpful in certain situations, such as treating conditions such as ADHD and narcolepsy, or providing a short-term boost in performance, they can also be dangerous when used improperly or excessively. It is important to speak with a healthcare professional before using any stimulant drug and to always follow dosage and usage instructions carefully.