Are you one of the millions of Americans who make dangerous mistakes with their medications? You can avoid that bitter pill with these simple strategies.

By Dana Sullivan Kilroy
Updated February 15, 2013
Serge Bloch

Your doctor writes a prescription; the pharmacist fills it; you take the medication and get better. That’s how it’s supposed to work. But in the real world, plenty can go wrong, and it regularly does: More than 1.5 million potentially dangerous drug mistakes occur every year, according to the Institute of Medicine, the health arm of the National Academy of Sciences. But with a little vigilance, you can make sure your medication leaves you healthier, not sicker. Here is a capsule review of the most common medication mistakes and how to properly take what’s prescribed to you. (Spoonful of sugar optional.)

Mistake No. 1: Assuming That the Drug You Take Home Is the One Your Doctor Prescribed

The fix: One out of every 20 prescriptions filled in a pharmacy has a mistake, according to statistics compiled by the Institute for Safe Medication Practices (ISMP), a nonprofit organization based in Horsham, Pennsylvania, that tracks medication errors. The pharmacist may choose the wrong product from a drop-down menu or misread the name of the drug on the prescription or on the bottle he is dispensing from. For example, your doctor may prescribe Lamisil for a nail infection but you receive Lamictal, a drug used to treat seizures. (See “Be on the Lookout for Look-Alikes,” on page 3, for other common Rx mix-ups.)

Write down the name and the dose of everything your doctor prescribes and know what each one is for. (And it can’t hurt to ask how to pronounce the names.) Then, at the pharmacy, double-check that you have the correct medications. If you’re taking a generic drug, check with the pharmacist that it’s the right one.

Mistake No. 2: Not Reading or Following the Instructions on the Drug’s Label and the FDA Leaflet

The fix: It’s “exceptionally rare” for someone to read the pamphlet that comes with a prescription medication, says Albert W. Wu, M.D., the director of the Center for Health Services and Outcomes Research at the Johns Hopkins Bloomberg School of Public Health, in Baltimore. No surprise—it is usually cluttered with chemistry-major language and not nearly as entertaining as Facebook. But it contains vital information that’s worth the slog.

Before you leave the counter, get a Cliffsnotes summary from the pharmacist. Ask her to go over the most important things you need to know, including the correct dosage, whether to take the medication with or without food, and if you should always use it at a certain time of day, says Allen Vaida, a pharmacist and the executive vice president of the ISMP. Find out about common side effects, whether it’s OK to drink alcohol, and what to do if you forget to take a dose. If the drug is administered via a patch, an inhaler, or some other device, ask for a demonstration.

All these details matter, since taking medicine is more like baking than cooking: You need to be exact. Just how important are even basic-sounding instructions? See below.

“Take at the same time every day”: Doses that are taken too close together could put excessive amounts of the compound into your system. Conversely, if you wait too long between doses, you may not have enough medication in your body for it to be effective.

“Take with food”: The medication may cause an upset stomach, or an empty stomach could interfere with the drug’s absorption, says Vaida. Other prescriptions bear the opposite warning and should not be taken with food. This is to minimize interactions or to help absorption.

“Avoid alcohol consumption”: This warning indicates the potential for harmful interactions, including enhancing side effects, such as drowsiness and dizziness; causing nausea and vomiting; and triggering a rapid heart rate.

“Do not chew or crush”: A crushed pill is absorbed more quickly, which could leave you with a dangerously high level of the drug. Be especially cautious of this when giving medicines to children. Another important point to keep in mind: If your doctor tells you to take the entire course of antibiotics, don’t stop when you start to feel better, and don’t save some for the next time you get sick. Skipping even one or two doses can allow the bacteria to survive and prolong your illness, and it may make your body resistant to stronger antibiotics.

Mistake No. 3: Not Keeping Track of All the Medicines You Use

The fix: Between vitamins and allergy medicines, birth control pills and painkillers, losing track of medications and supplements is easy to do. Plus, nearly half of women between the ages of 18 and 44 take at least one prescription drug, and that number climbs as we get older. More than a third of women age 45 and up take three or more.

“Some seemingly innocuous medications can interact with other drugs,” says L. Jo Parrish, a vice president of the Society for Women’s Health Research, in Washington, D.C. For instance, antacids can prevent antibiotics from being absorbed into the bloodstream. That can reduce the effectiveness of the antibiotic or prevent it from working at all. Antacids have the same effect on blood thinners and heart medications. And those aren’t the only troublemakers. Even a common decongestant can lead to a hazardous increase in blood pressure for people who take hypertension medication or MAO inhibitors (a type of antidepressant).

Certain foods can interfere with drugs as well: Grapefruit, of all things, blocks the enzyme that metabolizes certain drugs, including some antihistamines, sleeping pills, anti-anxiety medications, and some drugs that lower cholesterol and blood pressure, allowing the level of the drug to rise higher than it should.

The smartest solution is to write down everything you take, including products you use only occasionally. An easy tracking method is to keep the list of drugs on your phone (put it in your contacts under M, for medications). Record the names and the strengths of all drugs, vitamins, and supplements, plus how often you take them. If you have a smartphone, consider an app, like Pill Monitor (iPhone, $1) or MedCoach (Android and iPhone, free). “The apps function like personal medical records that are with you all the time,” says Wu. If you prefer pen and paper, print out the Food and Drug Administration’s helpful My Medicines chart, which you’ll find at Fill it out and keep it in your wallet.

“I tell patients to show the list of medications at every doctor visit, even if it’s a doctor you see all the time,” says Wu.

Mistake No. 4: Storing Medications Improperly and Keeping Them Too Long

The fix: Store medicines in their original bottles in a cool, dry place, such as a hallway linen closet, where they won’t be exposed to heat or moisture. (In fact, a typical medicine chest is one of the worst storage places, because a bathroom’s moisture can cause pills to deteriorate.) Keep them on a high shelf, away from the reach of children. Also, make sure to follow any refrigeration instructions. “Otherwise your medications can spoil and turn to soup,” says Wu.

Choose a large basket or a plastic box to use as your medicine chest, then do a sweep of the kitchen, the bathroom, your nightstand, desk drawers, and other places where you stash medications. (Don’t forget your purse.) Look at the date on each and dispose of any that have expired. “Some drugs lose their effectiveness over time, but others can become toxic,” says Wu. Unless otherwise specified on the label, the FDA doesn’t recommend flushing expired medications down the toilet. Instead, place them in a zippered plastic bag, throw in something undesirable, like used coffee grounds (to deter curious kids or pets), then toss the bag in the trash.

Be on the Lookout for Look-Alikes: What You Need vs. What You Get

Combine similar-sounding names with illegible handwriting and what might you get? The wrong medicine. Some common mix-ups.

Adderall for ADHD → Inderal for high blood pressure

Cafergot for migraines → Carafate for ulcers

Celexa for depression → Celebrex for arthritis

Doribax for kidney infections → Zovirax for herpes simplex

Femhrt for menopausal symptoms → Femara for breast cancer

Sarafem for PMS → Serophene for infertility

Zantac for ulcers → Xanax for anxiety