Drug combos can put seniors at risk

Jan 29, 2009 12:16 PM

My parents are visiting, and I know they've settled in because their pill boxes have found their usual spot on the kitchen counter. They use the type of box that has compartments for each day of the week to help them take the right pills at the right time. My parents, who are both over 70 and in good health, take only a few medications and supplements each. Even so, it can be easy to forget what to take when, so they rely on their boxes (and each other) to keep track.

Remembering daily doses isn't the only challenge of juggling multiple medications. Avoiding possible drug interactions is also a serious concern for older adults, as they use more drugs and dietary supplements than any other group. According to a recent study, more than 80 percent of adults aged 57 to 85 take at least one prescription medication and 30 percent take more than five. And among those taking prescription drugs, nearly 70 percent also regularly use over-the-counter medications or supplements. This can heighten their chance of a drug interaction, as their doctors and pharmacists may not know all the drugs and supplements they are taking.

Just because a medicine or supplement doesn't require a prescription, this doesn't mean it can't cause serious problems if combined with something else or not taken as directed. In fact, the study found that at least 1 in 25 older adults, or 2.2 million people, take drug combinations that can cause harmful interactions, and half of these interactions involve a nonprescription drug or supplement.

In total, the researchers found 46 potential interactions, many serious. Here are some of the most common ones they spotted.

Prescription-prescription interactions

Lisinopril (brand names Prinivil, Zestril) + potassium: this can cause raised potassium levels in the blood, potentially disrupting heart rhythm
Warfarin (Coumadin) + simvastatin (Zocor): this can cause bleeding

Prescription-nonprescription interactions

Warfarin + aspirin: this can cause bleeding
Atorvastatin (Lipitor) or simvastatin + niacin: this can cause muscle weakness and muscle breakdown

Nonprescription interactions

Ginkgo + aspirin: this can cause bleeding

What you need to know. Doctors and pharmacists are on the look out for possible drug interactions, but it's up to us, as patients, to keep them informed about all the over-the-counter medications and supplements we take. The authors of the study provide these tips:

Carry a list of all your medications and supplements in your wallet
Use the same pharmacy or chain for all your medications, so pharmacists will have a complete list of all the prescription drugs you're taking
Be sure to ask your doctor or pharmacist about possible interactions any time you start a new drug or supplement, regardless of whether it's prescribed.

Health professionals need to do their part, too, by staying on top of drug-safety information and regularly asking patients about what they're taking.

—Sophie Ramsey, patient editor, BMJ Group

ConsumerReportsHealth.org has partnered with The BMJ Group to monitor the latest medical research and assess the evidence to help you decide which news you should use.

Read more on prescription drug safety in our report "Dangerous drugs for older people," download our free Best Buy Drugs (PDF) report on managing multiple medicines, and use our Interaction Checker (subscribers only) to find out which herbs and supplements interact with your drugs.