An analgesic is any member of the diverse group of drugs used to relieve pain and to achieve analgesia. Analgesic drugs act in various ways on the peripheral and central nervous system; they include paracetamol (acetaminophen), the nonsteroidal anti-inflammatory drugs (NSAIDs) such as the salicylates, narcotic drugs such as morphine, synthetic drugs with narcotic properties such as tramadol, and various others. LSD and marijuana are used as hallucinogens. Hallucinogens are natural and synthetic (synthesized) substances that, when ingested (taken into the body), significantly alter one's state of consciousness. Hallucinogenic compounds often cause people to see (or think they see) random colours, patterns, events, and objects that do not exist. These substances are sometimes called "pyschedelic," or "mindexpanding" drugs.
Marijuana and hashish, two substances derived from the hemp plant (Cannabis sativa), are also considered natural hallucinogens. Marijuana (also called grass, pot, tea, weed, or reefer), a green herb from the flower of the hemp plant, is considered a mild hallucinogen. Hashish is marijuana in a more potent, concentrated form. Both drugs are usually smoked. Their effects include a feeling of relaxation, faster heart rate, the sensation that time is passing more slowly, and a greater sense of hearing, taste, touch, and smell. LSD (Lysergic Acid Diethylamide) is the most common hallucinogen and one of the most potent mood-changing chemicals. It is manufactured from lysergic acid, found in a fungus that grows on rye and other grains. LSD users may experience flashbacks of visions they had when on the drug. Some LSD users suffer organic brain damage, which results in impaired memory and attention span, confusion, and difficulty in thinking.