Amphetamines are very addictive stimulants that accelerate functions in the brain and body. They come in pills or tablets. Prescription diet pills also fall into this category of drugs.

No matter how a person takes amphetamines, these drugs hit with a fast high, making the user feel powerful, alert, and energized.

These "uppers" pump up heart rate, breathing, and blood pressure, and can also cause sweating, shaking, headaches, sleeplessness, and blurred vision.

Prolonged use may cause hallucinations and intense paranoia.

Users who stop taking amphetamines experience withdrawal symptoms, such as aggression, anxiety, and strong cravings for the drugs.