analgesic, any of a diverse group of drugs used to relieve pain. Analgesic drugs include the nonsteroidal anti-inflammatory drugs (NSAIDs) such as the salicylates, narcotic drugs such as morphine, and synthetic drugs with morphinelike action such as meperidine (Demerol) and propoxyphene (Darvon). Aspirin and other NSAIDs (e.g., acetaminophen, ibuprofen, and naproxen) reduce fever and inflammation as well as relieve pain. Narcotic analgesics and the morphinelike synthetic drugs depress the central nervous system and alter the perception of pain. They are used to alleviate pain not relieved by the NSAIDs. NSAIDs and other analgesics are also used in combination, as in Tylenol with codeine and Darvocet (Darvon and acetaminophen). Recently, patient-controlled analgesic techniques have been introduced, in which patients have the option of injecting small quantities of narcotic type analgesics to control their own pain. Microprocessor-controlled injections may be made through intravenous catheters, or through a catheter into the epidural (covering of the spinal cord) area. In addition to analgesic drugs, various techniques, such as acupuncture, hypnosis (see hypnotism), and biofeedback, are used to alleviate pain.

Drug that produces analgesia (see analgesic), narcosis (stupor or sleep), and drug addiction. In most people narcotics also produce euphoria. Those that occur naturally in the opium poppy, notably morphine, have been used since ancient Greek times. The main therapeutic use of narcotics is for pain relief. Most countries limit the production, sale, and use of narcotics because of their addictive properties and detrimental effects and the incidence of drug abuse. With the development in the 19th century of the hypodermic needle and of heroin, five to 10 times as potent as morphine, the use and abuse of narcotics increased dramatically. A narcotic overdose can cause central nervous system depression, respiratory failure, and death.

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Drug that relieves pain without blocking nerve impulse conduction or markedly altering sensory function (see nervous system). Two classes are defined by the type of pain-relieving action. Opioids (opiates and synthetic narcotics; see opium) act on brain receptors to inhibit pain impulses. They may be used for short- or long-term pain relief, usually by prescription, but carry a risk of drug addiction. Nonopioids, used mostly for short-term relief and modest pain, are available without prescription. They include NSAIDs (including aspirin and ibuprofen) and acetaminophen; all act by inhibiting synthesis of prostaglandins, molecules involved in the peripheral perception of pain.

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