Snake oil is a term used to describe deceptive marketing, health care fraud, or a scam. Similarly, snake oil salesman is a common label used to describe someone who sells, promotes, or is a general proponent of some valueless or fraudulent cure, remedy, or solution. The term comes from the "snake oil" that used to be sold as a cure-all elixir for many kinds of physiological problems. Many 19th-century United States and 18th-century European entrepreneurs advertised and sold mineral oil as "snake oil liniment", making claims about its efficacy as a panacea. Patent medicines that claimed to be a panacea were extremely common from the 18th century until the 20th, particularly among vendors masking addictive drugs such as cocaine, amphetamine, alcohol, and opium-based concoctions or elixirs, to be sold at medicine shows as medication or products promoting health.

Medicine shows were touring acts that peddled "miracle cure" patent medicines and other products between various entertainments. They developed from European mountebank shows and were common in the United States in the nineteenth century, especially in the Old West.