In the early 1900s, German scientist Paul Ehrlich described an ideal drug as a "magic bullet." Such a drug would be aimed precisely at a disease site and would not harm healthy tissues. Although many new drugs are aimed more accurately than their predecessors, none of them, as of yet, hit the target exclusively.
Most drugs produce several effects, but usually only one effect—the therapeutic effect—is wanted for the treatment of a disorder. The other effects may be regarded as unwanted, whether they are intrinsically harmful or not. For example, certain antihistamines cause drowsiness as well as control the symptoms of allergies. When an over-the-counter sleep aid containing an antihistamine is taken, drowsiness is considered a therapeutic effect. But when an antihistamine is taken to control allergy symptoms during the daytime, drowsiness is considered an annoying, unwanted effect.
Most people, including health care practitioners, refer to unwanted effects as side effects; another term used is adverse drug effect. However, the term adverse drug reaction is technically more appropriate for drug effects that are unwanted, unpleasant, noxious, or potentially harmful.
Prevalence of adverse drug reactions
Not surprisingly, adverse drug reactions are common. Most adverse drug reactions are relatively mild, and many disappear when the drug is stopped or the dose is changed. Some gradually subside as the body adjusts to the drug. Other adverse drug reactions are more serious and last longer. About 3 to 7% of all hospital admissions in the United States are for treatment of adverse drug reactions. Adverse drug reactions occur during 10 to 20% of hospital admissions, and about 10 to 20% of these reactions are severe. These statistics do not include the number of adverse drug reactions that occur in people who live in nursing homes and other care facilities.
Although the exact number of adverse drug reactions is not certain, they clearly represent a significant public health problem that is often preventable.
Common adverse drug reactions
Digestive disturbances—loss of appetite, nausea, a bloating sensation, constipation, and diarrhea—are particularly common adverse drug reactions, because most drugs are taken by mouth and pass through the digestive tract. However, almost any organ system can be affected. In older people (see Aging and Drugs), the brain is commonly affected, often resulting in drowsiness and confusion.
Identification and reporting of adverse drug reactions
Many adverse drug reactions are identified when a drug is being tested before it is submitted to the Food and Drug Administration (FDA) for approval. Other adverse drug reactions, typically those that are uncommon, are not detected until the drug has been on the market long enough to be used by a large number of people. Thus, health care providers are required to report suspected adverse drug reactions to the FDA.
Some Serious Adverse Drug Reactions
Adverse Drug Reaction |
Types of Drugs |
Examples |
|
Anemia (resulting from decreased production or increased destruction of red blood cells) |
Certain antibiotics |
Chloramphenicol |
|
Drugs used to treat malaria or tuberculosis in people with G6PD enzyme deficiency |
Chloroquine Isoniazid Primaquine |
|
|
Angioedema (swelling of the lips, tongue, and throat causing difficulty breathing) |
ACE inhibitors |
Captopril Enalapril Lisinopril |
|
Proton pump inhibitors |
Esomeprazole Lansoprazole Omeprazole |
|
|
Birth control drugs (all forms including patches and pills) |
Drospirenone/ethinyl estradiol Norelgestromin/ethinyl estradiol |
|
|
Confusion and drowsiness |
Sedatives, including many antihistamines |
Diphenhydramine |
|
Antidepressants (especially in older people) |
Amitriptyline Imipramine |
|
|
Decreased production of white blood cells, with increased risk of infection |
Certain antipsychotic drugs |
Clozapine |
|
Chemotherapy drugs |
Cyclophosphamide Mercaptopurine Methotrexate Vinblastine |
|
|
Some drugs used to treat thyroid disorders |
Propylthiouracil |
|
|
NSAIDs (repeated use of excessive doses) |
Ibuprofen Naproxen |
|
|
Aminoglycoside antibiotics |
Gentamicin Tobramycin |
|
|
Some chemotherapy drugs |
Cisplatin Methotrexate |
|
|
Antifungals |
Amphotericin B |
|
|
Some antibiotics |
Gentamicin Tetracycline (outdated) |
|
|
Some analgesics |
Acetaminophen (use of excessive doses) |
|
|
Some drugs used to treat tuberculosis |
Isoniazid |
|
|
Iron supplements (in excessive amounts) |
Ferrous sulfate, ferrous fumarate |
|
|
Antidepressants |
Duloxetine |
|
|
Antibiotics |
Tetracycline |
|
|
Muscle tissue destruction (rhabdomyolysis) |
Statins |
Atorvastatin Simvastatin |
|
Stomach or intestinal ulcers (with or without bleeding) |
NSAIDs |
Aspirin Ibuprofen Naproxen |
|
Anticoagulants |
Heparin Warfarin |
|
|
Bisphosphonates |
Alendronate Risedronate |
|
|
Some antibiotics |
Penicillins Quinolones Sulfonamides |
|
|
Anticonvulsants |
Phenytoin Valproic acid |
|
|
Antiarrhythmics |
Amiodarone Procainamide Sotalol |
|
|
Antipsychotics |
Chlorpromazine Haloperidol Lithium |
|
|
ACE = angiotensin-converting enzyme; G6PD = glucose-6-phosphate dehydrogenase; NSAIDs = nonsteroidal anti-inflammatory drugs. |
||
More Information
The following are some English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
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American Association of Poison Control Centers: Access to information on a variety of poisons, an emergency helpline (1-800-222-1222), and tips on prevention.
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FDA Adverse Event Reporting System: Access to Questions and Answers on FDA's Adverse Event Reporting System (FAERS).
Drugs Mentioned In This Article
| Generic Name | Select Brand Names |
|---|---|
Cyclophosphamide |
CYTOXAN (LYOPHILIZED) |
ferrous fumarate |
No US brand name |
Mercaptopurine |
PURINETHOL |
Acetaminophen |
TYLENOL |
Tetracycline |
ACHROMYCIN V |
Esomeprazole |
NEXIUM |
Lansoprazole |
PREVACID |
Methotrexate |
OTREXUP |
Atorvastatin |
LIPITOR |
Risedronate |
ACTONEL |
Alendronate |
FOSAMAX |
Haloperidol |
HALDOL |
Simvastatin |
ZOCOR |
Chloroquine |
ARALEN |
Duloxetine |
CYMBALTA |
Tobramycin |
TOBI, TOBREX |
Imipramine |
TOFRANIL |
Gentamicin |
GENOPTIC |
Amiodarone |
CORDARONE |
Omeprazole |
PRILOSEC |
Lisinopril |
PRINIVIL, ZESTRIL |
Cisplatin |
PLATINOL |
Isoniazid |
LANIAZID |
Ibuprofen |
ADVIL, MOTRIN IB |
Enalapril |
VASOTEC |
Clozapine |
CLOZARIL |
Phenytoin |
DILANTIN |
estradiol |
ESTRADERM, ESTROGEL, VIVELLE |
Captopril |
CAPOTEN |
Naproxen |
ALEVE, NAPROSYN |
Warfarin |
COUMADIN |
Lithium |
LITHOBID |
Sotalol |
BETAPACE |
Heparin |
PANHEPRIN |
