This chapter examines drugs and health. It does not focus on alcohol or tobacco, as these are discussed in depth in other chapters. It notes how drugs may be categorised as natural, synthetic, for medicinal use, for recreational use, psychoactive or non-psychoactive. In the UK, most drugs are ‘controlled’ by law. The seven types of drugs, depressants, stimulants, opioids, cannabinoids, hallucinogens, nitrites and performance- and image-enhancing drugs, are described along with their health effects. The chapter includes self-medication and other reasons why drug use starts and why it might become a disorder or dependence. Health risks associated with drug use include routes of administration, substance-linked sex, pregnancy, co-occurring mental health problems, adulterants, poly-drug use and death. The stigma associated with drug use encourages health risks and is one of the greatest barriers to people accessing help. It outlines the argument why drug use is a public health issue.