Arthritis Today

The Dangers of Mixing Medication

One body, multiple drugs: It can be a recipe for disaster.


Arthritis patient Edith Manley of San Leandro, Calif., is exceedingly careful when mixing medication, and with good reason. Nearly three years ago, Manley's 39-year-old daughter, Megan Nelson, died unexpectedly during a visit to Manley's home. Nelson had back pain for several years and occasional bouts of depression. Although her medical conditions weren't fatal, mixing prescriptions apparently was. "She was taking antidepressants for her depression and painkillers for her back pain," recalls Manley. "Her primary cause of death was listed as an accidental drug overdose.”

Manley and Nelson's teenage son, Mike, still grieve. And Manley is determined to get the word out: Mixing medications can be deadly, especially for people with arthritis or older Americans, who often have more than one health condition that requires medication.

Multiple Meds = Increased Dangers

Oscar Gluck, MD, clinical professor of medicine at the University of Arizona School of Medicine and director of the Arizona Rheumatology Center in Phoenix, says most of his patients have several diseases. In addition to a rheumatic disease, the most common diseases his patients have are diabetes, hypertension or cardiovascular disease. Although people of any age can have multiple health problems, the greatest risk is among those 50 and older, he says. As people age, their propensity to develop other health problems – and the likelihood that they are mixing medication – increases.

A recent study of adults in the United States showed that more than 90 percent of people 65 or older use at least one medication per week. More than 40 percent use five or more medications, and 10 percent use 12 or more.

"It's not unusual to see people with arthritis taking a dozen drugs. And if they're taking that many, I can usually find three or four that have the potential to interact," says Don Miller, professor and chairman of pharmacy practice in the College of Pharmacy Practice at North Dakota State University and pharmacotherapy specialist at Veterans Administration Hospital in Fargo.

Obviously, the more drugs you need to take, the more likely you are to be taking two that don't mix. But even if you are young, relatively healthy and just occasionally take medications for other problems, such as a cold, headache or infection, you could be at risk for medication reactions – if you and your doctor aren't careful. 

The Actions of Interactions

Bad interactions from mixing prescriptions can occur not only when you are taking more than one drug – and not just literally at the same time – but also when you're taking medications as well as consuming alcohol or supplements. Miller says St. John's wort is one of the most common offenders. And the more drugs and supplements you add to your personal mix, the higher your risk of a dangerous effect climbs. Not all interactions are so blatant or their potential consequences life threatening. Nevertheless, if you want to get the greatest benefits of your medication with the least possible risks, all interactions bear watching.

Taking two or more medications can lead to a drug-drug interaction that can block the effect of one of the drugs you're taking – meaning it becomes ineffective and you don't get what you need – or it can cause too much of one drug to remain in your system or essentially produce an overdose. For example, if you take allopurinol (Lopurin or Zyloprim) for gout and add the immunosuppressive drug azathioprine (Imuran) to treat severe rheumatoid arthritis (RA), the azathioprine can further suppress your immune system, possibly putting you at risk of a serious infection. And both aspirin and the blood-thinning drug warfarin (Coumadin) decrease your blood's ability to clot, so if you're taking warfarin for cardiovascular disease and aspirin to ease arthritis pain, you could be unwittingly setting yourself up for a life-threatening bleeding episode.

Reducing the Risks

The FDA recently took an important step toward reducing the risk of drug interactions and other medication errors – at least in hospitals – by proposing a rule requiring bar codes on all medication packages. The mandate would require bar codes to include the National Drug Code (NDC), a system that contains the drug's name, dosage, form and strength. Bar code readers in hospitals would ensure that patients were getting the actual drug they were prescribed and could check for potential interactions between prescribed medications.

The FDA mandate is a step in the right direction, but the only way to completely eliminate the risk of mixing prescriptions is to completely eliminate your drugs –  hardly an option if you need medications to live and function. But there are ways you and your doctor can minimize the risk. 

What Your Doctor Can Do

Eliminate the unnecessary. Are you still filling a prescription your doctor wrote five years ago? Have you even forgotten what a particular medication is for? There's a chance you may no longer need the medication or that there are newer or safer alternatives to it. Taking outdated, unnecessary medications is a particular problem for elderly patients. Richard Ackerman, MD, professor of family medicine at Mercer University School of Medicine in Macon, Ga., says that some older patients accumulate medications over decades.

Adjust the timing. Some medications interfere with others by keeping them from being absorbed in the intestine. For example, antacids can interfere with the body's absorption of tetracycline and some other antibiotics. In those cases, just adjusting the timing a bit – taking one drug an hour or two after the other – will alleviate the problem.

Change the dosage – or the drug. Sometimes two drugs interact to increase or decrease the effectiveness of one another. "NSAIDs, for example, can blunt the effects of drugs that treat high blood pressure, sometimes making it necessary to increase the dosage of the blood pressure medication," says Dr. Gluck. If a drug increases the effect of another, lowering the dose of one may help. In other cases, your doctor can switch you to a different drug that provides the benefits of the original drug without the interaction risk.

Monitor closely. In some cases you need all of the drugs you are taking, even if they have the potential to interact. When that happens, your doctor will need to monitor you closely, usually through frequent, regular blood tests. Unless a problem is actually detected, the risk of taking you off a medication – or perhaps even changing the dosage – may be worse than the risk of interactions.

Add another medication. Although this is usually the choice of last resort, doctors must sometimes prescribe a third medication to help alleviate the problems that an interaction between two other drugs is causing. For example, if you need both NSAIDs and corticosteroids, yet taking them together causes stomach upset or increases your risk of developing a stomach ulcer, your doctor may prescribe a third drug such as cimetidine (Tagamet), omeprazole (Prilosec) or lansoprazole (Prevacid) to ease your stomach upset and reduce your ulcer risk.

Only your doctor can make these changes, but there are several things you can do on your own to make dangerous interactions less likely.

What You Can Do

Stick with one pharmacy. Choose one pharmacy to get your prescriptions filled and stay with it. Most pharmacies have computer programs that alert the pharmacist if another prescription(s) you had filled at that pharmacy has the potential to react with your newest prescription.

Brown bag it. Once a year fill a bag with all of the medications and supplements you are taking and have your pharmacist check them. The bag will contain the information – names of drugs, supplements and their dosages – that your pharmacist needs to determine if drug interactions are likely.

Have one doctor coordinate your care. Sometimes people end up taking unnecessary medications or potentially dangerous combinations of medicines because multiple doctors are prescribing them without being aware of what other doctors are prescribing. If you have one doctor – usually an internist or family physician – who coordinates your care and is aware of all the medications you take, he or she can alert you to possible interactions.

Speak up. Every time a doctor writes a new prescription, remind her of the supplements and medications - prescription and nonprescription – you are already taking. "I use a Palm Pilot to check the Physicians' Desk Reference (Thompson, 2003) for potential drug interactions every time I prescribe a new medication," says Dr. Gluck.

Be mindful of potential interactions. If two drugs you are taking have the potential to interact, ask your doctor what symptoms you should watch for. Keep in mind that interactions aren't always immediate, nor are they always evident. But knowing what to watch for can help ensure you get medical attention (including a dosage or medication change) if you need it.