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A component of the Canadian Medication Incident Reporting and Prevention System (CMIRPS).

SafeMedicationUse Newsletter

Is My Medication Affecting the Way My Heart Beats?


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QT prolongation is a problem with the electrical signal in the heart that affects the heart's rhythm. In some people, QT prolongation can create a feeling like the heart is racing. It can also make a person feel light-headed or dizzy, or they could suddenly faint. Others who have this electrical signal problem may not have any symptoms at all. There are many causes for QT prolongation, including some medications.

Problems with QT prolongation are more likely when people take multiple medications that can cause this effect. For some people, if steps are not taken to lower the risk, life-threatening heart problems can occur. has the following suggestions to help identify if your medications could increase the risk of QT prolongation:

  • Keep an up-to-date list of all the medications you take, including nonprescription and natural health products. Show this list to your health care providers each time you start a new medication or product.
  • Use the 5 Questions to Ask to get information about side effects (including QT prolongation) of any medication or product you are taking, and any tests that you might need.
  • Fill all your prescriptions at the same pharmacy so the pharmacist can see if you are taking more than one medication that causes QT prolongation. If you cannot fill a needed prescription at your usual pharmacy, share your updated medication list with both pharmacies.
  • If you have started a new medication and experience any of the symptoms mentioned above, contact your health care provider.

Medication safety bulletins contribute to Global Patient Safety Alerts

This newsletter was developed in collaboration with Best Medicines Coalition and Patients for Patient Safety Canada.

Recommendations are shared with healthcare providers, through the ISMP Canada Safety Bulletin, so that changes can be made together.

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