Khat is a stimulant drug that speeds up the messages between the brain and the body. It is a leafy green plant containing two main stimulant drugs, cathinone and cathine, which produce the stimulant effects. The buds and leaves of the khat plant (Catha edulis) are chewed for stimulant and euphoric effects, and traditionally have been used for medicinal purposes as well as recreationally. Khat is part of some social traditions in parts of the Middle East, such as Saudi Arabia and Yemen, and in Eastern Africa, such as Somalia.

Khat can be chewed fresh or preserved by wrapping freshly picked khat in banana leaves and then used dried. The effects of khat usually last between 90 minutes and 3 hours. Short-term effects of khat may include increased talkativeness, feeling energetic and social, alertness and improved concentration, faster heartbeat and breathing, and slightly higher temperature and blood pressure. However, khat can also cause many side effects including mood changes, hyperactivity, aggressiveness, anxiety, depression, high blood pressure, manic behavior, paranoia, and psychosis. Severe side effects from khat include migraine, bleeding in the brain, heart attack, changes to blood vessels, lung problems, liver damage, and changes in sex drive and sexual performance.

Khat is illegal in some countries, including the US and Canada, but legal in some European countries. It is classified as a Class C drug in the UK, which means it is illegal to have for yourself, give away or sell.