Risk associated with medical interventions

• Adverse effects of prescription drugs or vaccines
• Overuse of drugs (causing, for example, antibiotic resistance in bacteria)
• Prescription drug interaction

Medical errors

• Incorrect prescription, perhaps due to illegible handwriting or computer typos
• Faulty procedures, techniques, information, methods, or equipment
• Negligence
• Hospital-acquired infections

Medical error and negligence

Iatrogenic conditions need not result from medical errors, such as mistakes made in surgery, or the prescription or dispensing of the wrong therapy, such as a drug. In fact, intrinsic and sometimes adverse effects of a medical treatment are iatrogenic. For example, radiation therapy and chemotherapy—necessarily aggressive for therapeutic effect – frequently produce such iatrogenic effects as hair loss, hemolytic anemia, diabetes insipidus, vomiting, nausea, brain damage, lymphedema, infertility, etc. The loss of function resulting from the required removal of a diseased organ is iatrogenic, as in the case of diabetes consequential to the removal of all or part of the pancreas.

The incidence of iatrogenesis may be misleading in some cases. For example, a ruptured aortic aneurysm is fatal in most cases; the survival rate for treatment of a ruptured aortic aneurysm is under 25%. Patients who die during or after an operation will still be considered iatrogenic deaths, but the procedure itself remains a better bet than the probability of death if left untreated.

Other situations may involve actual negligence or faulty procedures, such as when pharmacotherapists produce handwritten prescriptions for drugs.

Another situation may involve negligence where patients are brushed off and not given proper care due to providers holding prejudice for reasons such as sexual orientation, ethnicity, religion, immigration status, etc. This can cause mistrust between patients and providers, leading to patients to not go in for treatment, resulting in more deaths.

Adverse effects

A very common iatrogenic effect is caused by drug interaction, i.e., when pharmacotherapists fail to check for all medications a patient is taking and prescribe new ones that interact agonistically or antagonistically (thereby potentiating or attenuating the intended therapeutic effect). Such situations can cause significant morbidity and mortality. Adverse reactions, such as allergic reactions to drugs, even when unexpected by pharmacotherapists, are also classified as iatrogenic.

The evolution of antibiotic resistance in bacteria is iatrogenic as well.^[9] Bacterial strains resistant to antibiotics have evolved in response to the over prescription of antibiotic drugs.^[10]

Certain drugs and vaccines are toxic in their own right in therapeutic doses because of their mechanism of action. Alkylating antineoplastic agents, for example, cause DNA damage, which is more harmful to cancer cells than regular cells. However, alkylation causes severe side-effects and is actually carcinogenic in its own right, with potential to lead to the development of secondary tumors. In a similar manner, arsenic-based medications like melarsoprol, used to treat trypanosomiasis, can cause arsenic poisoning.

Adverse effects can appear mechanically. The design of some surgical instruments may be decades old, hence certain adverse effects (such as tissue trauma) may never have been properly characterized.

Psychiatry

In psychiatry, iatrogenesis can occur due to misdiagnosis (including diagnosis with a false condition, as was the case of hystero-epilepsy^[11]). An example of a potentially iatrogenic circumstance is misdiagnosis of bipolar disorder for another disorder, especially in pediatric patients considered to have major depressive disorder and prescribed stimulants or antidepressants.^[12] Other conditions such as somatoform disorder and chronic fatigue syndrome are theorized to have significant sociocultural and iatrogenic components.^[13] Post-traumatic stress disorder is hypothesized to be prone to iatrogenic complications based on treatment modality.^[14] Certain antipsychotics have been shown to reduce brain volumes in animals and in humans over long-term use.^[15][16]

Some populations may be at risk of underdiagnosis or misdiagnosis of psychiatric disorders, including those identified as having substance abuse disorders.^[17] At the other end of the spectrum, dissociative identity disorder is considered by a minority of theorists to be a wholly iatrogenic disorder with the bulk of diagnoses arising from a tiny fraction of practitioners.^[11][18]

The degree of association of any particular condition with iatrogenesis is unclear and in some cases controversial. The over-diagnosis of psychiatric conditions (with the assignment of mental illness terminology) may relate primarily to clinician dependence on subjective criteria.^[19] The assignment of pathological nomenclature is rarely a benign process and can easily rise to the level of emotional iatrogenesis, especially when no alternatives outside of the diagnostic naming process have been considered. Many former patients come to the conclusion that their difficulties are largely the result of the power relationships inherent in psychiatric treatment, which has led to the rise of the anti-psychiatry movement.^[20][21]

Iatrogenic poverty

Meessen et al. used the term "iatrogenic poverty" to describe impoverishment induced by medical care.^[22] Impoverishment is described for households exposed to catastrophic health expenditure^[23] or to hardship financing.^[24] Every year, worldwide, over 100,000 households fall into poverty due to health care expenses. A study reported that in the United States in 2001, illness and medical debt caused half of all personal bankruptcies.^[25] Especially in countries in economic transition, the willingness to pay for health care is increasing, and the supply side does not stay behind and develops very fast. But the regulatory and protective capacity in those countries is often lagging behind. Patients easily fall into a vicious cycle of illness, ineffective therapies, consumption of savings, indebtedness, sale of productive assets, and eventually poverty.

Social and cultural iatrogenesis

The 20th-century social critic Ivan Illich broadened the concept of medical iatrogenesis in his 1974 book Medical Nemesis: The Expropriation of Health^[26] by defining it at three levels.

• First, clinical iatrogenesis is the injury done to patients by ineffective, unsafe, and erroneous treatments as described above. In this regard, he described the need for evidence-based medicine 20 years before the term was coined.^[27]
• Second, at another level social iatrogenesis is the medicalization of life in which medical professionals, pharmaceutical companies, and medical device companies have a vested interest in sponsoring sickness by creating unrealistic health demands that require more treatments or treating non-diseases that are part of the normal human experience, such as age-related declines. In this way, aspects of medical practice and medical industries can produce social harm in which society members ultimately become less healthy or excessively dependent on institutional care. He argued that medical education of physicians contributes to medicalization of society because they are trained predominantly for diagnosing and treating illness, therefore they focus on disease rather than on health. Iatrogenic poverty (above) can be considered a specific manifestation of social iatrogenesis.
• Third, cultural iatrogenesis refers to the destruction of traditional ways of dealing with, and making sense of, death, suffering, and sickness. In this way the medicalization of life leads to cultural harm as society members lose their autonomous coping skills. It is worth noting that in these critiques "Illich does not reject all benefits of modern society but rejects those that involve unwarranted dependency and exploitation."^[28]