Adverse Drug Effects

“An adverse drug reaction is any unexpected, unintended, undesired, or excessive response to a medicine that results in temporary or permanent harm, disability, or death. An adverse drug reaction may result in a need for a visit to the emergency room or a stay in the hospital. The medicine may also need to be discontinued or changed.”

American Society of Health-System Pharmacists. ASHP guidelines on adverse drug reaction monitoring and reporting. Am J Health-Syst Pharm. 1995; 52:417-9.

“Any symptom in an elderly patient should be considered a drug side effect until proved otherwise.”

Gurwitz J, Monane M, Monane S, Avorn J. Polypharmacy. In: Morris JN, Lipsitz LA, Murphy K, Bellville-Taylor P, eds. Quality Care in the Nursing Home. St. Louis, MO: Mosby-Year Book; 1997:13-25.

“The average American is ten times more likely to be hospitalized from an adverse drug reaction than from a motor vehicle accident.”

Moore Thomas J. Prescription for Disaster, Simon & Schuster, NY:1998, p. 49.

“10.7% of hospital admissions in older adults are associated with adverse drug reactions.”

Kongkaew C, et al. Hospital admissions associated with adverse drug reactions: a systematic review of prospective observational studies. Ann Pharmacother 2008;42:1017-25.

Almost every medicine has a risk of causing some type of adverse drug effect. Some medicines have a higher risk than others. When deciding whether to prescribe a medicine, the doctor must balance the risk of adverse drug effects against the benefit that the medicine can provide for the person.

In older adults, who are more likely to take multiple medicines, the doctor must also consider the cumulative effects of all the medicines the person is taking. It may be that each medicine would be appropriate when used alone, but the combination of all the medicines may cause problems.

Medicines can interact with one another or can have similar side effects that cause problems for the person taking them. For example, the medicine regimen may increase the risk of falls or may cause constipation or mental confusion.


Examples of adverse drug effects

After being diagnosed with epilepsy, John is started on Depakote® (valproic acid) to prevent seizures. One month later, a blood test shows that John’s liver enzymes have gone up quite a bit. The doctor decides that continuing the Depakote® might lead to liver damage, and changes the Depakote® to another medicine.

Martha has been taking Aleve® (naproxen sodium) on a regular basis for several years to manage her arthritis symptoms. One day she develops severe stomach pain and goes to the emergency room. The doctor there discovers that Martha has an ulcer in her stomach that was caused by the Aleve®.

Mary developed a urinary tract infection and her doctor prescribed Bactrim® (sulfamethoxazole-trimethoprim). When she developed a skin rash from the Bactrim®, the doctor took her off it and changed her to a different antibiotic.

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