quacks

Quacks refers to individuals who pose as medical experts or offer health-related services or products without legitimate credentials or evidence of safety and efficacy. They often promise quick cures for serious diseases, rely on testimonials rather than scientific data, and promote unproven remedies, devices, or regimens.

The term quack derives from the onomatopoeic sound of a duck's quack; in English it has been used since the 17th or 18th century to describe impostors who practice medicine or sell bogus cures.

Throughout history, quackery has taken many forms, from itinerant healers and patent medicines in the 18th–19th centuries to today’s dietary supplements and online advertising. In many countries, regulatory reforms and licensure for physicians and pharmacists curtailed overt practices of quackery, though illegal advertising and fraud still occur.

Modern quackery persists in various forms, including unverified medical devices, unproven therapies, and dubious online health claims. Consumers are advised to verify credentials, consult licensed professionals, and evaluate evidence from independent sources; regulatory bodies and patient advocacy groups monitor and prosecute false claims.

Related topics include charlatanism and patent medicines.