Scottsdale, Arizona - Older adults need to be especially vigilant about drug safety, according to the December issue of Mayo Clinic Health Letter. That’s because older adults are more likely to be taking more than one medication at a time. Interactions between drugs can cause side effects that might not occur if a drug were taken alone. And, physical changes in older adults can alter both the effectiveness of a medication and side effects, compared with what a younger adult might experience.

Consider these myths and facts:

Myth: If a drug works well at a certain dose, taking more will be better.

Fact: With many drugs, the benefit won’t increase after a certain dose, but the risks will. For example, taking two acetaminophen (Tylenol, others) provides pain relief with minimal risk of side effects. Taking four acetaminophen pills doesn’t improve pain relief and greatly increases the risk of harmful side effects and toxicity. Taking too high of a dose of some medications can be especially harmful in older adults. Liver and kidney functions can diminish over time and reduce the body’s ability to process and eliminate a drug.

Myth: A drug taken at a certain dose for years can’t cause new side effects.

Fact: A drug taken without problems for years could be the cause of troubling new side effects in older adults. With increased age, body weight may change. Digestion, circulation, and kidney and liver function may slow down. These changes can affect the processing, circulation and excretion of drugs and make the drug more or less effective than it was in the past. Adding new drugs, nonprescription medications, herbal or dietary supplements or alcohol could lead to interactions and possibly new side effects.

Myth: It’s obvious when something is a side effect of a drug or a symptom of a disease or condition.

Fact: Side effects of certain drugs can be mistaken for diseases or conditions associated with aging or even for symptoms that are chalked up to “getting older.” Side effects of certain drugs also can worsen symptoms of an existing disease or condition. Doctors and pharmacists can refer to lists of drugs that should be used with caution or avoided in older adults. But no list can account for every particular situation. Patients, doctors and pharmacists should always consider the possibility that any symptom or signs of “old age” such as weakness, drowsiness, confusion, anxiety or memory loss could be a drug side effect.