The opening chapter presents basic information on alcoholic beverages, including definitions of alcohol (ethanol), use, abuse, and dependence. The measurement of alcohol concentrations in body products is also reviewed. The second chapter begins the scientific discussion of alcohol, including explanations of the relationship between alcohol and accidental injuries and alcohol's effects on organ systems and risk for certain cancers. This is followed by a chapter that focuses on the effects of alcohol and other drug use on neuropsychological functioning. It notes that drugs produce a more generalized, pervasive effect on the brain, unlike the effects produced on tissue and organs. The fourth chapter reviews the effects of alcohol on neuron signaling, neurotransmitter function, and alcoholic brain damage and cognitive dysfunction. The next chapter details the neuroanatomical and neurobehavioral effects on a fetus of the mother's heavy alcohol use. A chapter on the effects of marijuana relies on recently available information to discuss its impact on the respiratory system, immune system, cardiovascular system, hormones and fertility, and perinatal conditions. The examination of opium and its derivatives in chapter 7, along with methadone pharmacotherapy, begins with a discussion of the worst direct medication consequences of heroin, i.e., death, and concludes with a discussion of the indirect causes of medical illness that result from heroin use. These include infection and contamination with adulterants used to cut the drug. Methadone is compared with heroin throughout the chapter regarding effects on organ system function and dysfunction. Chapter 8 focuses on the detrimental effects of cocaine, and briefly discusses methamphetamine and phenylpropanolamine. Attention is given to adverse effects on the cardiovascular, neurologic, and pulmonary systems. Cocaine's effects are also considered for the genitourinary, gastrointestinal, hepatic, pancreatic, and ocular systems, as well as a fetus. Another chapter addresses the prenatal effects of nicotine, cocaine, marijuana, and opiate drugs. The final chapter identifies the medical consequences of inhalants, which typically contain compounds that are extremely organotoxic. Chapter references and a subject index