W hether it’s an over-the-counter pain reliever or a prescription statin to lower cholesterol, medication has a troubling downside: the risk of side effects.

Side effects are the expected (and usually unwanted) reactions you hear rattled off in TV drug ads: constipation, diarrhea, dizziness, drowsiness, dry mouth, nausea, upset stomach, and more. Though some are not serious and are likely to subside over time, some may be especially problematic for older adults.

More on Prescription Drugs

According to the Centers for Disease Control and Prevention, older adults are twice as likely as other adults to suffer an adverse drug event serious enough to require a trip to the emergency room, and seven times more likely than younger adults to be hospitalized as a result.

One possible reason is that “as you age, you’re facing more conditions and taking more drugs to treat them,” says Michael Steinman, M.D., a professor of medicine at the University of California, San Francisco. According to a March 2016 study in JAMA Internal Medicine, 88 percent of adults age 62 to 85 take at least one prescription drug regularly.

“And the more medications you take, the greater the likelihood of multiple, often compounded effects,” Steinman adds.

At the same time, other age-related factors can play a role in how medication affects you. Here, we explain what to know about side effects and the steps you can take to reduce your risk.

Increased Potency for Older Adults

As you age, your body often gains more fat and holds less water than it once did—all of which can cause drugs to become more concentrated. And medication can linger longer in your system, which can further increase the risk and severity of side effects.

“The key organs that are responsible for breaking down medications, mainly the liver and the kidneys, begin to function more slowly,” explains Michael Hochman, M.D., M.P.H., an associate professor of clinical medicine at the Keck School of Medicine at the University of Southern California. “As a result, medications don’t get excreted as quickly.” (Conversely, he adds, medication might not be effectively absorbed into the bloodstream, which could reduce a drug’s effectiveness.)

The problem of a drug sticking around longer in your system is particularly concerning with certain kinds. All sedative drugs used to treat insomnia, for example, such as prescription zolpidem (Ambien and generic) and eszopiclone (Lunesta and generic) and the over-the-counter sleep drug diphenhydramine (Benadryl Allergy, Nytol, Sominex, and generic), are particularly risky. That's because older adults are likely to be more sensitive to their sedating effects, which can increase the risk for falls and other accidents.

If you have other health concerns, such as persistent dizziness, weakness, poor balance due to arthritis, ear and eye problems, cognitive decline, or other chronic conditions, side effects from some medication can exacerbate them.

Some blood-pressure-lowering drugs, for example, tend to lower blood pressure much more significantly in older people than in younger people, which can increase the risk of dizziness, weakness, and falls.

In a study of almost 5,000 older adults published in JAMA Internal Medicine in 2014, Yale School of Medicine researchers found that seniors taking blood pressure medication had a 30 to 40 percent higher risk of having a serious injury from a fall than those who weren’t taking the drugs.

Leading Culprits

Sometimes drugs that pose the most serious side effects may also have major benefits. Doctors often refer to these as “high ­benefit, high ­risk” medications.

At the top of the list of drugs that require regular monitoring to minimize the risks, according to the CDC, are blood thinners to prevent heart attacks, strokes, and blood clots, such as warfarin (Coumadin, Jantoven, and generic); diabetes drugs such as insulin; drugs used to treat high blood pressure and heart disease, including antiarrhythmic agents such as digoxin; and seizure medicines like phenytoin (Dilantin and generic) and carbamazepine (Tegretol and generic).

Opioid painkillers are also more likely than other drugs to cause potentially dangerous side effects for seniors, especially when taken long term or at higher doses. Oxycodone (OxyContin and generic), oxycodone combined with acetaminophen (Percocet and generic), and hydro­codone combined with acetaminophen (Vicodin and generic) and other opioid pain medicine, for example, commonly cause constipation, nausea, and drowsiness or a “fuzzy-headed” feeling. The CDC notes that even when taken as directed, opioids can lead to physical dependence, drug overdose, and possibly death.

Talk About Side Effects With Your Doctor

In a recent nationally representative Consumer Reports telephone survey of 1,063 U.S. adults, we found that those 65 and older who regularly take prescription medicine were also less likely to discuss the potential for side effects with their doctor. Barely half of seniors said they discussed such safety concerns; two-thirds of younger adults did.

People may be embarrassed at having a certain problem or may not recognize it as a side effect. “They may think they’re experiencing a symptom of their condition, or that it’s just due to old age,” Steinman adds.

If you notice a physical or mental change that’s bothersome, bring it up with your doctor. “Even if the drug is working, talk to your doctor about trying a lower dose or a different medication, to see if you can minimize the risk of side effects,” Hochman explains.

And ask about nondrug options, such as exercise to lower blood cholesterol levels and high blood pressure, bladder training for an overactive bladder, or cognitive therapy for insomnia or depression, for example. “Nonpharmacologic therapies can be very effective and without side effect,” he says.

Even if you don't notice side effects, ask for a review of all your prescription and over-the-counter meds, vitamins, and supplements at every doctor’s visit to make sure they’re not interacting in dangerous ways. Your doctor might also recommend stopping a drug that’s no longer needed, reducing the number of meds you take.

And Take These Safety Steps

Keep a list. Include every drug and supplement you take, the dosages, when you take them, the shape and color of your meds, the name of the prescribing physician, and whether you should take them with food or drink. Note your pharmacy’s phone number, any allergies you have, and emergency contact info.

Understand side effects and warnings. Research shows that many people often misinterpret drug labels.

Skip alcohol. Mixing it with certain drugs can worsen dizziness or lightheadedness, or increase or decrease a med’s potency.

Don’t stop a drug on your own. Doing so can lead to withdrawal symptoms and worsen the condition the drug was intended to treat. Unless you develop wheezing, blisters, swelling, or any severe or life-threatening effects such as difficulty breathing, call your doctor before stopping.

Editor's Note: This article also appeared in the November 2017 issue of Consumer Reports on Health.