Medical procedures Surgery may have a number of undesirable or harmful effects, such as
infection,
hemorrhage,
inflammation,
scarring, loss of function, or changes in local
blood flow. They can be reversible or irreversible, and a compromise must be found by the physician and the patient between the beneficial or life-saving consequences of surgery versus its adverse effects. For example, a limb may be lost to
amputation in case of untreatable
gangrene, but the patient's life is saved. Presently, one of the greatest advantages of
minimally invasive surgery, such as
laparoscopic surgery, is the reduction of adverse effects. Other nonsurgical physical procedures, such as high-intensity
radiation therapy, may cause
burns and alterations in the
skin. In general, these therapies try to avoid damage to healthy
tissues while maximizing the therapeutic effect.
Vaccination may have adverse effects due to the nature of its biological preparation, sometimes using
attenuated pathogens and
toxins. Common adverse effects may be
fever,
malaise and local reactions in the vaccination site. Very rarely, there is a serious adverse effect, such as
eczema vaccinatum, a severe, sometimes fatal complication which may result in persons who have
eczema or atopic
dermatitis.
Diagnostic procedures may also have adverse effects, depending much on whether they are
invasive,
minimally invasive or
noninvasive. For example,
allergic reactions to
radiocontrast materials often occur, and a
colonoscopy may cause the perforation of the
intestinal wall.
Medications Adverse effects can occur as a collateral or side effect of many interventions, but they are particularly important in
pharmacology, due to its wider, and sometimes uncontrollable, use by way of
self-medication. Thus,
responsible drug use becomes an important issue here. Adverse effects, like
therapeutic effects of drugs, are a function of
dosage or drug levels at the target
organs, so they may be avoided or decreased by means of careful and precise
pharmacokinetics, the change of drug levels in the organism in function of time after administration. Adverse effects may also be caused by
drug interaction. This often occurs when patients fail to inform their physician and pharmacist of all the medications they are taking, including herbal and dietary supplements. The new medication may interact agonistically or antagonistically (potentiate or decrease the intended therapeutic effect), causing significant
morbidity and mortality around the world. Drug-drug and food-drug interactions may occur, and so-called "natural drugs" used in
alternative medicine can have dangerous adverse effects. For example, extracts of
St John's wort (
Hypericum perforatum), a
phytotherapic used for treating mild
depression are known to cause an increase in the
cytochrome P450 enzymes responsible for the
metabolism and elimination of many drugs, so patients taking it are likely to experience a reduction in
blood levels of drugs they are taking for other purposes, such as
cancer chemotherapeutic drugs,
protease inhibitors for
HIV and
hormonal contraceptives. The scientific field of activity associated with drug safety is increasingly government-regulated, and is of major concern for the public, as well as to
drug manufacturers. The distinction between adverse and nonadverse effects is a major undertaking when a new drug is developed and tested before
marketing it. This is done in
toxicity studies to determine the nonadverse effect level (NOAEL). These studies are used to define the dosage to be used in human testing (phase I), as well as to calculate the maximum admissible daily intake. Imperfections in clinical trials, such as insufficient number of patients or short duration, sometimes lead to
public health disasters, such as those of
fenfluramine (the so-called
fen-phen episode),
thalidomide and, more recently, of
cerivastatin (Baycol, Lipobay) and
rofecoxib (Vioxx), where drastic adverse effects were observed, such as
teratogenesis,
pulmonary hypertension,
stroke,
heart disease,
neuropathy, and a significant number of deaths, causing the forced or voluntary
withdrawal of the drug from the market. Most drugs have a large list of nonsevere or mild adverse effects which do not rule out continued usage. These effects, which have a widely variable incidence according to individual sensitivity, include
nausea,
dizziness,
diarrhea,
malaise,
vomiting,
headache,
dermatitis, dry mouth, etc. These can be considered a form of pseudo-allergic reaction, as not all users experience these effects; many users experience none at all. The Medication Appropriateness Tool for Comorbid Health Conditions in Dementia (
MATCH-D) warns that people with dementia are more likely to experience adverse effects, and that they are less likely to be able to reliably report symptoms.
Examples with specific medications •
Abortion,
miscarriage or
uterine hemorrhage associated with
misoprostol (Cytotec), a labor-inducing drug (this is a case where the adverse effect has been used legally and illegally for performing abortions) •
Addiction to many
sedatives and
analgesics, such as
diazepam,
morphine, etc. •
Birth defects associated with
thalidomide •
Bleeding of the
intestine associated with
aspirin therapy •
Cardiovascular disease associated with
COX-2 inhibitors (i.e. Vioxx) •
Deafness and
kidney failure associated with
gentamicin (an
antibiotic) •
Death, following
sedation, in children using
propofol (Diprivan) •
Depression or
hepatic injury caused by
interferon •
Diabetes caused by
atypical antipsychotic medications (neuroleptic
psychiatric drugs) •
Diarrhea caused by the use of
orlistat (Xenical) •
Erectile dysfunction associated with many drugs, such as
antidepressants •
Fever associated with
vaccination •
Glaucoma associated with
corticosteroid-based
eye drops •
Hair loss and
anemia may be caused by
chemotherapy against
cancer,
leukemia, etc. •
Headache following
spinal anaesthesia •
Hypertension in
ephedrine users, which prompted FDA to remove the
dietary supplement status of
ephedra extracts •
Insomnia caused by stimulants,
methylphenidate (Ritalin),
Adderall, etc. •
Lactic acidosis associated with the use of
stavudine (Zerit, for
HIV therapy) or
metformin (for diabetes) •
Mania caused by
corticosteroids •
Liver damage from
paracetamol •
Melasma and
thrombosis associated with use of estrogen-containing
hormonal contraception, such as the
combined oral contraceptive pill •
Priapism associated with the use of
sildenafil •
Rhabdomyolysis associated with
statins (anti
cholesterol drugs) •
Seizures caused by withdrawal from
benzodiazepines •
Drowsiness or increase in
appetite due to
antihistamine use. Some antihistamines are used in sleep aids explicitly because they cause drowsiness. •
Stroke or
heart attack associated with
sildenafil (Viagra), when used with
nitroglycerin •
Suicide, increased tendency associated to the use of
fluoxetine and other
selective serotonin reuptake inhibitor (SSRI) antidepressants •
Tardive dyskinesia associated with use of
metoclopramide and many
antipsychotic medications ==Controversies==