Iatrogenesis refers to harm to health caused by medical treatment or medical personnel. Causes include negligence, improper sanitation, medical error, poor medical procedures, lack of medical information, misdiagnosis, adverse effects of drugs, and drug interactions. Health problems and symptoms caused by iatrogenesis are called iatrogenic artifacts. Historically, iatrogenesis was a major cause of mortality due to the poor sanitation of doctors and their ignorance of the germ theory of medicine. This has been greatly alleviated in modern times, but iatrogenesis remains a major cause of illness and death.
Some iatrogenesis is the expected but undesirable result of treatment. In the case of drugs, this is called adverse drug reaction. Many drugs have significant side effects and some are only effective in doses high enough to be toxic to humans. The chemicals used in chemotherapy are especially damaging to cancerous cells, but they damage healthy tissue, as well, and some are themselves carcinogenic.
Other adverse effects from drugs are the result of medical error. Doctors may prescribe the wrong drugs or incorrect dosages. Treating a patient with multiple drugs simultaneously, called polypharmacy, can result in dangerous drug interactions if the doctor and pharmacist are not careful about what drugs are given together. Iatrogenic illness can even be caused by poor penmanship, as seen in cases where patients have been given the wrong drugs by pharmacists due to the illegible handwriting of the prescribing doctor.
Iatrogenesis can be caused by the error or negligence of medical professionals in other ways. Mistakes in diagnosis can result in unnecessary medical procedures or in patients being given unnecessary drugs that might have serious side effects. Iatrogenesis can be caused by surgical errors, such as performing a procedure on the wrong patient, performing a procedure incorrectly, operating on the wrong part of the body, or leaving an object, such as a surgical sponge, inside the patient.
Hospital patients that are left lying in the same position for too long can develop pressure ulcers, better known as bedsores, which can cause serious injury and lead to potentially lethal infections. Medical errors can lead to what is called a cascade effect. This effect is where an initial mistake in diagnosis or treatment causes health problems or the appearance of health problems that lead to additional medical procedures that in turn cause further damage to the patient's health.
Some iatrogenesis is psychological in origin. Much like when the health of a patient who is given a placebo sometimes improves because of the patient's belief that the placebo is real medicine, patients may actually suffer symptoms of illnesses and disorders they don't have because their doctor has convinced them that they are afflicted by it due to a diagnostic error. Iatrogenic artifacts also include "diseases" created by and diagnosed by doctors that do not actually exist naturally, such as "hystero-epilepsy," and are instead the product of mistaken beliefs about causation or how the body works, or of the doctor's cultural environment. Due to the power of suggestion, this can result in seemingly genuine cases of nonexistent diseases and disorders.