An analgesic is a medication used to relieve or eliminate pain without loss of consciousness. Analgesics can be divided into two main groups: non-opioids, which include nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, acetaminophen (paracetamol), etc., and opioids, which include morphine and codeine and their derivatives. These drugs work by blocking the transmission of pain signals in the central nervous system (CNS) or by altering the perception of pain in the brain. The use of analgesics should be monitored by medical professionals, as improper or excessive use can lead to side effects, including dependence, deterioration of kidney or liver function, and other health risks.