Anesthetic, any agent that produces a local or general loss of sensation, including pain. Anesthetics achieve this effect by acting on the brain or peripheral nervous system to suppress responses to sensory stimulation. This unresponsive state is known as anesthesia.

Different types of anesthesia work in different ways. Some anesthetic medications numb certain parts of your body. Other anesthetics numb your brain so you can sleep through more invasive surgical procedures.