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SafeMedicationUse Newsletter

Minerals May Interact with Some Medicines Don't Forget — Keep a List of Your Medicines!


A Canadian who had the bad luck to get pneumonia in Florida almost had a second dose of bad luck because of a drug interaction. A doctor wrote a prescription for the antibiotic moxifloxacin (brand name Avelox) and a pharmacist then prepared the medicine. However, the doctor and the pharmacist didn't know that the patient was already taking a product that contained multivitamins and minerals. Mineral supplements can keep the body from absorbing some drugs, including Avelox. This means that the drugs can't do their jobs. In this case, the patient took all of the Avelox exactly as the doctor instructed, but the pneumonia was not cured. When the doctor prescribed Avelox again, the pharmacist told a family member that it was important to stop taking any minerals while taking Avelox. The patient stopped taking the minerals while he was taking the Avelox and the pneumonia was cured.

Consumers who are asked for a list of their medicines sometimes forget to mention nonprescription medicines. Some people may not think of vitamins, minerals, and other natural products as medicines. Other things that might be overlooked are medicines that are inhaled, injected, or applied to the skin, eyes, ears, or nose. Even medicines that are taken only once in a while can be important.

When you are sick, it is easy to forget things. That's one reason that ISMP Canada suggests making a list of all your medicines and how you take them. Your list should include your name and other important information like your medical conditions, your allergies, and previous drug reactions.

Keep the list with you at all times. Show the list to your doctor, nurse, pharmacist, or any other healthcare professional every time you receive care. That way, your healthcare professional will know what medicines you are taking and how you take them. This can prevent a mistake, such as receiving two medicines that shouldn't be taken together, getting a medicine that will cause an allergic reaction, or not receiving a medicine that you need when you are in hospital.

Whenever you begin taking a new medicine, add it to the list. You should include every type of medicine, even products that you can buy without a prescription. Don't forget things like:
  • prescription drugs (drugs that the doctor prescribes for you)
  • painkillers, such as ASA (brand names Aspirin or Anacin) acetaminophen (brand name Tylenol), ibuprofen (brand names Advil or Motrin), and naproxen (brand names Aleve or Naprosyn)
  • Cough and cold medicine
  • Allergy medicine
  • Stomach medicine (such as medicine for heartburn)
  • Laxatives
  • Birth control pills
  • Vitamins and mineral supplements (such as iron, magnesium, calcium)
  • Herbal products
  • Eye, ear, and nose drops
  • Inhalers ("puffers")
  • Sprays
  • Patches
  • Ointments, creams, and lotions
  • Injections

A useful Medication Record Book, prepared by Canada's Research-Based Pharmaceutical Companies (Rx&D) in partnership with the Canadian Medical Association and the Canadian Pharmaceutical Association is available through the following link:

The Manitoba Institute for Patient Safety has also created some helpful forms and wallet cards that you can use for your list of medicines. These are available from the "It's Safe to Ask" website:

Editor's note: This report also raised a question about Avelox being prescribed a second time for this consumer. We don't have all of the details about the case, so there might have been a good reason for this. However, our expert reviewers felt that a different antibiotic should have been prescribed when the Avelox did not work the first time. This might have reduced the chances of antibiotic resistance or adverse drug events. For this reason, and as a reminder of the importance of keeping drug-mineral interactions in mind, we are also sharing this newsletter with healthcare practitioners.

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