Every year, thousands of people combine drugs they are taking with other medications or foods that produce negative reactions. In most cases, they weren’t aware there would be a problem, since the medications and foods seemed harmless.
Here are just some of the most common hazardous drug interactions and what you can do to protect yourself and your family from harm.
Drug/food interactions
No doubt your pharmacist has cautioned you to avoid taking certain antibiotics with dairy products. This combination can reduce the effectiveness of the medications.
But many pharmacists and doctors are unaware of some unusual drug/food interactions. Foods that could cause problems with some medications
• Grapefruit and grapefruit juice
Grapefruit and grapefruit juice contain compounds that can interact powerfully with medications and cause devastating side effects.
Example: Blood pressure medications, such as Procardia and Adalat (nifedipine) and Plendil (felodipine), are dangerous when combined with grapefruit, resulting in higher blood levels of blood pressure medications. Symptoms may include facial flushing, nausea, dizziness, confusion, palpitations or irregular heartbeat.
• Green, leafy vegetables
Green, leafy vegetables such as broccoli, brussels sprouts and cabbage reduce the effectiveness of the blood thinner Coumadin ( warfarin), a commonly prescribed blood thinner that prevents blood clots. These foods are rich in vitamin K, which helps the blood to clot. Coumadin, meanwhile, works by counteracting vitamin K’s clotting action.
Consuming a small amount of vitamin K-rich foods daily probably won’t pose a problem. But if you usually skip these vegetables and then overindulge, at a Chinese restaurant, for example, you reduce the drug’s effectiveness and put yourself at risk for a blood clot or stroke.
• Oatmeal and other high-fiber foods
Oatmeal and other high-fiber foods may interfere with the absorption of Lanoxin (digoxin), a drug prescribed to control an irregular heart rhythm, which can lead to blood clots and stroke. Take Lanoxin two or three hours before or after eating high-fiber foods.
• Salt substitutes
Salt substitutes are used by people with high blood pressure. But they contain high amounts of potassium. If consumed with potassium-sparing diuretics such as Aldactone (,spironolactone) which are prescribed for high blood pressure or congestive heart failure they can cause potassium levels to soar, increasing the risk of cardiac arrest.
• Licorice and Lanoxin
Licorice and Lanoxin or a diuretic like Lasix (furosemide) can lead to low levels of potassium, causing irregular heart rhythms and cardiac arrest. One piece of licorice probably won’t hurt but regular handfuls of licorice could be deadly.
Prescription drug interactions
- Antibiotics vs. blood thinners
Antibiotics like Flagyl and Protostat (metronidazole,) can cause problems when taken with the blood thinner Coumadin. The antibiotics prevent the body from purging Coumadin, and if Coumadin levels get too high, life-threatening bleeding could occur.
If you are taking both metronidazole and Coumadin, you must be monitored carefully by your physician and have frequent blood tests.
Rx/Otc Drug Interaction
Don’t assume over-the-counter (OTC) medications are risk-free. Teamed with certain prescription drugs, some can cause complications. Examples
• Pain relievers
Aspirin, Advil and Nuprin (ibuprofen) Aleve (naproxen) and Orudis KT (ketoprofen) can reduce the effectiveness of beta-blockers, such as Inderal (propranolol) and Lopressor (metoprolol), which are prescribed to treat high blood pressure.
If this happens, blood pressure can rise, increasing the risk of heart attack and stroke. If you are taking a beta-blocker, check with your doctor before adding a pain reliever. If your doctor prescribes a beta-blocker and aspirin, he/she should monitor your blood pressure.
• Antacids
Antacids can inhibit the absorption of the heart and blood pressure medications Capoten (captopril) and Tenormin (atenolol), as well as Lanoxin.
And the activated charcoal added to counteract gas may reduce the effectiveness of a number of drugs, including tricyclic antidepressants such as Elavil (amitriptyline) and the diabetes medications Diabinese (chlorpropamide) and Tolinase (tolazamide.)
• Allergy and cough/cold remedies
Allergy and cough/cold remedies that contain pseudoephedrine, ephedrine or phenylephrine should not be combined with a monoamine oxidase inhibitor antidepressant like Nardil (phenelzine) or Parnate (tranylcypromine). Your blood pressure could soar, leading to a hypertensive crisis and stroke.
Guarding against Interactions
- Make your doctors aware of the prescription and OTC drugs you are taking and have your doctors check for interaction potential. Ask them to consult drug reference books and/or computer reference programs before you leave the office.
- Have all prescriptions filled at a single pharmacy, preferably one that keeps computerized data on all your medications and can zero in on possible interactions. Tell your pharmacist about OTC drugs you are taking.
- Make a list of key questions to ask. When a new drug is prescribed, don’t assume doctors and pharmacists are aware of every drug interaction or if they are, that they will remember to alert you.
List the following questions and give copies to your doctor and pharmacist to fill out independently. If one contradicts the other, speak with both to get the correct answer.
- What is the medication’s name?
- What is the dose?
- What time(s) should I take it?
- Should I take it with food? After eating? Before eating? How long?
- Should I avoid any foods?
- Are there vitamins or supplements I should avoid? Increase?
- Are there any precautions or warnings I should know about?
- Are there any contraindications that would make this drug inappropriate?
- What other prescription medicines should I avoid?
- Are there any OTC remedies I should avoid?
- What side effects are common with my medicine?
- Are there any side effects that are so serious you would want to know about them immediately?
If your doctor or pharmacist tells you that a drug won’t interact adversely with another medication or food, don’t assume that no interactions exist. Though rare, life-threatening interactions can go undetected by drug companies, the medical establishment and the Food and Drug Administration for months or even years after a drug hits the market.
So if you experience any strange symptoms that cannot be easily explained, ask your doctor to contact the drug’s manufacturer and file a report with the FDA.
