Defined by the manifestation of new undesirable symptoms following drug intake, drug iatrogenism constitutes a public health problem, in particular in the elderly and in children. Any unexpected effect must be reported by the caregiver to the Pharmacovigilance Center. 

Iatrogenic diseases are the set of unwanted symptoms that occur alongside the symptoms of the disease being treated as a result of drug therapy. In fact, drugs that are effective against certain diseases can cause undesirable side effects, which vary from person to person, and which can affect the health of the patient being treated. They can take various forms such as a skin rash due to a drug allergy, a surge in blood pressure or a digestive hemorrhagic accident.

These side effects are frequent and most of them are listed on the instructions for prescribed drugs. A regional pharmacovigilance center collects all reports from health professionals and is updated regularly. The aim of this database is to prevent these risks of iatrogenic diseases, which are often underestimated, and thus lead either to a change in treatment or to an adjustment (reduction and spacing of doses, taking the drug in the middle of a meal. or with another protective medication…).

The elderly are the most affected by iatrogenic diseases, because they are often polymedicated (several drugs to be taken at the same time) and more vulnerable. These side effects are twice as frequent after 65 years and 20% of these side effects lead to hospitalizations.

The causes of iatrogenic diseases are multiple:

• Overdose: there is a risk of overdose in the event of uncontrolled drug intake due to cognitive disorders (thought disorders) common in the elderly.
• Allergy or intolerance: to certain drugs such as antibiotics, anti-inflammatory drugs, pain-relieving drugs (analgesics), chemotherapy, contraception, certain ointments, etc. can occur. These allergies and intolerances remain very variable from one person to another.
• Slowed elimination: there is also a risk of reducing the pathways of elimination of drug molecules by the liver or kidneys, leading to drug overdose in the body.
• Drug interactions: There may be a drug interaction between two or more drugs taken at the same time.
• Modification of the metabolism: by certain drugs such as diuretics, laxatives, treatments for the thyroid gland, etc.
• Self-medication: which interferes with prescribed treatment or poor adherence to medication.
• Unsuitable dosages in children or the elderly, depending on age and weight.

These causes are at the origin of drug iatrogenism which can often be corrected, but which also sometimes lead to more severe iatrogenic accidents.

This diagnosis of iatrogenic diseases is made when symptoms appear that do not correspond to the disease being treated. Dizziness, falls, faintness, intense fatigue, diarrhea, constipation, sometimes bloody vomiting etc. So many symptoms that should alert the patient and the doctor. 

The questioning, the clinical examination, the drugs taken, especially if they are recent, will guide the diagnosis and the additional examinations to be carried out. Stopping the suspected drug is the first step to take.

If this discontinuation is followed by an improvement or even a disappearance of the symptoms of iatrogenic diseases, the diagnosis is made by a therapeutic test (discontinuation of treatment). It will then be necessary to write down the drug causing this side effect and avoid prescribing it again. An alternative will have to be found.

• Confusion and cognitive disorders following the prescription of diuretics which will promote the occurrence of a drop in sodium in the blood (hyponatremia) and dehydration;
• Gastrointestinal bleeding after taking anti-inflammatory drugs indicating a lesion or even a digestive ulcer;
• Rash, difficulty in breathing and swelling of the face after taking antibiotics which indicate an allergy to this antibiotic;
• Malaise following vaccination and edema at the injection site due to an allergy to the vaccine;
• Oral or gynecological mycosis following antibiotic therapy, the origin of which is an imbalance of the oral or gynecological flora following treatment.

The treatment of the side effects of a treatment will most often involve stopping the treatment and looking for an alternative to the treatment. But it can also be to anticipate this side effect by prescribing another drug such as an anti-ulcer when prescribing anti-inflammatory drugs or antimycotics during antibiotic treatment.

Other times, it will be sufficient to correct the imbalance caused by the drug, such as giving sodium or potassium in the event of a blood disorder (hyponatremia or hypokalaemia). 

A mild laxative may also be prescribed in the presence of constipation following drug treatment or a transit retarder in the event of diarrhea. 

A diet can also be put in place (low-salt diet, banana for a potassium contribution, diet low in saturated fat in the event of an increase in cholesterol, etc.). 

Finally, treatment to normalize blood pressure figures may be prescribed with regular monitoring.