For practical purposes, any drug man be considered as belonging to one of four types, as the following: No Medical Value These drugs do not have a well-establish medicinal value, but pose little danger of abuse. Many readily available herbal remedies and homeopathic treatments fall into this category. Their manufactures are not allowed to claim on the label that the drug as any medicinal value. Medical Value, Very Low Abuse Drugs that have medicinal value, but are not commonly abused fit into this category. These medications include the majority of over-the-counter remedies and prescription medications. A physician's prescription may be required to avoid incorrect us, not abuse. Anticancer drugs, for example, have little risk of abuse, but can cause severe illness if used inappropriately. Medical Value, High Abuse Drugs that have medical value, but also have a high risk of abuse potential fit into this category. These drugs are specified in the Controlled Substance Act. To prescribe them, a physican requires a lecense from the Drug Enforcemnt Adminstration, known more commonly as the DEA. Controlled substances are listed in five Schedules, based on their abuse potential. Those listed in Schedule V have the lowest risk of abuse and include medicines such as cough syurp with dextromethorphan. Drugs in Schedule IV and lll have an increasing likelihood of abuse. Schedule ll drugs have a very high acuse potential but also have some use as medicines, and include drugs such as cocaine and morphine. No Medical Value, High Abuse Drugs that have no accepted medicinal value, and a high risk of abuse. These drugs are listed as Schedule l. They are illegal except for use in extremly limited circumstance, such as authorized research. Schedule l drugs include herion, LSD-25, and cannabis sativa. Controlled SubstancesAll drugs illegal in the United States can be considered psychoactive drugs,because all of them affect the central nervous system. In the CSA, they are organized into four basic categories: Opiates and Opioids Opiates are drugs derived from opium. They are amound the oldest drugs in existence and were the first to be seen as a major public health threat. They include herion, morphine, and codeine. Opioids are completely synthetic drugs and are not derived from opium. However, they are similar to the opiates in their chemical structure and biological effects. Common opioids include meperidine, known as Demerol and also the drug Fentanyl. For convenience, the term opiates usually refers to both opiates and opioids. There are may variations and derivatives of opiates--this category accounts for 122 of the 178 drugs that are illegal in the United States. Hallucinogens These are drugs sometimes called psychedelics or psychomimetics. They are grouped in this category because their cheif feature is to cause altered perceptions. Well-known members include LSD-25, PCP, psilocybin, mescaline, and marijuana. Hallucinogen is the designation used by the U.S. government and also the most common term in medical research. There are several objections to the term. By referring primarily to visual distortions ot other changes in sensation, the importance of mood and thought changes in understated. Some drugs classified as hallucinogens (such as MDA, DOET,ect.) can enhance self-awareness and intesify feelings without producing sensory changes at all. Stimulants This is a general category of drugs that excite the central nervous system. Often referred to as "uppers", they include cocaine, Amphetamine, MDMA, and methylphenidate. Depressants These drugs inhibit the central nervous system. They include sedatives (with calming and relaxing effects) and hypnotics (known as sleeping pills) and are often reffered to as "downers". Barbiturates, GHB, and Benzodiazepines fall right into this category. with a little help from: Paul Gahlinher M.D. Ph.D.