The Catholic social theorist Ivan Illich subjected contemporary western medicine to detailed attack in his Medical Nemesis, first published in 1975. He argued that the medicalization in recent decades of so many of life's vicissitudes — birth and death, for example — frequently caused more harm than good and rendered many people in effect lifelong patients. He marshalled a body of statistics to show what he considered the shocking extent of post-operative side-effects and drug-induced illness in advanced industrial society. He was the first to introduce to a wider public the notion of iatrogenesis.^[38] Others have since voiced similar views, but none so trenchantly, perhaps, as Illich.^[39]

Through the course of the twentieth century, healthcare providers focused increasingly on the technology that was enabling them to make dramatic improvements in patients' health. The ensuing development of a more mechanistic, detached practice, with the perception of an attendant loss of patient-focused care, known as the medical model of health, led to criticisms that medicine was neglecting a holisticmodel.^{[citation needed]} The inability of modern medicine to properly address some common complaints continues to prompt many people to seek support from alternative medicine. Although most alternative approaches lack scientific validation, some, notably acupuncture for some conditions and certain herbs, are backed by evidence.^[40]

Medical errors and overmedication are also the focus of complaints and negative coverage. Practitioners of human factors engineering believe that there is much that medicine may usefully gain by emulating concepts in aviation safety, where it is recognized that it is dangerous to place too much responsibility on one "superhuman" individual and expect him or her not to make errors. Reporting systems and checking mechanisms are becoming more common in identifying sources of error and improving practice. Clinical versus statistical, algorithmic diagnostic methods were famously examined in psychiatric practice in a 1954 book by Paul E. Meehl, which found statistical methods superior.^[41] A 2000 meta-analysis comparing these methods in both psychology and medicine found that statistical or "mechanical" diagnostic methods were, in general, although not always, superior.^[41]

Disparities in quality of care given are often an additional cause of controversy.^[42] For example, elderly mentally ill patients received poorer care during hospitalization in a 2008 study.^[43] Rural poor African-American men were used in a study of syphilis that denied them basic medical care.