What Are Drug Interactions and Medication Conflicts?

Taking Drugs in Combination with Other Things Can Make Us Sick

glass of grapefruit juice
Some foods and all alcoholic beverages can increase how the body metabolizes some drugs. Grapefruit juice is one example. Armstrong Studios/Photolibrary/Getty Images

If you take a prescription or an over-the-counter drug, and you can answer yes to any of these questions, then you may be experiencing a drug interaction or conflict that is having an negative affect on your health:

  • Do you take more than one drug - prescription or over-the-counter?
  • Do you take vitamins or other supplements?
  • Do you ever drink grapefruit juice, eat licorice or chocolate?
  • Do you enjoy a glass of wine, a bottle of beer or another alcoholic beverage?

    Drug-to-drug, drug-to-supplement, drug-to-food and drug-to-alcohol conflicts and interactions may simply give you a bit of intestinal discomfort - or they may kill you.

    We hear too frequently in the news about a celebrity who has died because of conflicts from drugs. Sometimes we hear them labeled as overdoses. But overdoses can result from a drug that was taken in its prescribed quantity, then its effect was altered by the presence of another substance like another drug or alcohol. Michael Jackson, Heath Ledger, Anna Nicole Smith, and others are all considered to have died from drug interactions.

    Here are some examples of medication conflicts and drug interactions that may surprise you.

    Medication Conflicts: Drug with Other Drug

    If you take more than one drug, then your drugs may be getting in each other's way. The more medications you take, the more chances there are of conflicts. According to the Institute for Safe Medication practices, almost 40% of Americans take four or more different drugs.

    Here are some examples of problems that can occur when two conflicting drugs are taken by the same patient:

    • Antihistamines:  These over-the-counter drugs we take for runny noses, sneezing, congestion or watery eyes, can increase the depressive effects of many sedatives, tranquilizers, high blood-pressure medications or medicines for depression. In turn, that makes patients sleepier and more fatigued, which can be deadly to the patient or others if the patient tries to drive a car, operate heavy machinery or any other activity that requires concentration. Antihistamines can also cause an increase in blood pressure or speed up the heart rate of patients who take blood pressure-reducing medications.
    • Acid reducers like Prilosec (omeprazole), Nexium or others known as drugs to treat GERD (gastrointestinal esophageal reflux disease) will interact with any drug that contains cimetidine, such as some asthma drugs, seizure drugs or warfarin (Coumadin), used as a blood thinner.
    • Cardorone (also called amiodarone) conflicts with the cholesterol-lowering drug, Zocor (simvastatin) and can lead to kidney failure or death if the dose of Zocor is 20 mg or higher. Cardarone also conflicts with Coumadin.

    There may be thousands of examples of these interaction problems. Be sure to double check any possible conflicts before you begin taking a new drug that could possibly conflict with a drug you already take.

    Medication Conflicts: Drug with Vitamins, Minerals or Herbal Supplement

    At least 50% of Americans take dietary supplements according to the federal government. Vitamins, minerals, amino acids, herbs, botanicals and other substances that many of us call "natural" are being ingested in hopes of improving our health.

    Whether or not most of them truly help us is not the question here. But whether or not they might have an impact on the effectiveness of drugs we take is something we must all be concerned with.

    Here are some examples of drug and supplement conflicts:

    • Vitamin E and gingko biloba can interact with Coumadin (also called warfarin, Jantoven, Marevan, Lawarin, Waran and Warfant), increasing its blood-thinning properties and putting those who take it at risk for increased bleeding.
    • Ginseng also interacts with Coumadin. In addition, it creates potential bleeding problems for people who take heparin, aspirin or NSIADs (ibuprofen, naproxen and others). Ginseng can cause headaches, nervousness or hyperactivity among those who take MAO inhibitors.
    • St. John's Wort may create problems for those who take antidepressants.

      Medication Conflicts: Drug with Food and Alcohol

      According to the Food and Drug Administration, some foods and all alcoholic beverages can increase how the body metabolizes some drugs, meaning the drug will be absorbed and used by the body in a different way than it was intended to. This can increase, decrease or neutralize the effect of the drug.

      Here are some examples:

      • Grapefruit juice can cause problems for people who take certain blood-pressure lowering medications or for those who take cyclosporine after an organ transplant. There may be dozens of other drugs that grapefruit juice affects, causing problems for those who drink it along with those drugs.
      • Chocolate - who can live without chocolate? Some of us need to - because the drugs we take will become problematic if we eat chocolate, too. For example, anyone (including children) who takes a stimulant drug such as Ritalin or a sedative-type drug like Ambien must avoid any food that includes caffeine, including chocolate and coffee.
      • Chocolate can also cause problems for anyone who takes MAO inhibitors for depression or Parkinson's disease. MAO inhibitors include drugs like Nardil (phenelzine) or Parnate (tranylcypromine). In fact, chocolate isn't the only food that needs to be avoided by those who take MAO inhibitors. Here is a list of foods to avoid, which include smoked, aged or pickled meat or fish, sauerkraut, aged cheeses, beef or chicken liver and red wines.
      • Licorice, another favorite, needs to be avoided by people who take certain blood-pressure lowering drugs like digitalis (also called digoxin, digitoxin, Cardoxin, Digitek, Lanoxicaps or Lanoxin.)

      With so many ways to negatively affect the drugs we take to improve our health, it makes sense to avoid those drug conflicts and interactions. Whenever your provider gives you a new prescription for a drug, or if you decide to use an over-the-counter drug to address difficult symptoms, be sure you make yourself aware of the potential conflicts, then avoid them.


      From the American Academy of Family Physicians

      From Medline Plus (National Library of Medicine)

      From the FDA

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