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Preventing Harm from Drug Interactions:
Consumers Can Play an Important Role

2012-06-14

SafeMedicationUse.ca has received a report from a consumer who was given two medicines that are known to interact with each other. This type of problem is known as a drug interaction. A drug interaction occurs when the actions of one medicine affect the actions of another medicine.

The consumer had received a prescription for tamoxifen from a cancer specialist. Tamoxifen is a medicine that is used to treat certain types of breast cancer. Later, the consumer's family doctor prescribed duloxetine (brand name Cymbalta) to treat depression. Duloxetine can reduce the effectiveness of tamoxifen. The consumer took both of these medicines for several months before finding out about the drug interaction during a follow-up visit with the cancer specialist. The cancer specialist told the consumer to stop taking the tamoxifen and prescribed a different breast cancer medicine that does not interact with duloxetine.

Drug interactions can occur with many types of medicines, including over-the-counter and natural or herbal medicines, as well as prescription medicines. Some medicines may also interact with specific foods or alcohol. Drug interactions can be harmful. Some drug interactions require that a different medicine be prescribed, as in the example described here. On the other hand, not all drug interactions mean that you have to stop taking the medicines that interact. Sometimes, you can keep taking the medicines, but a different dose will be prescribed. Sometimes the potential drug interaction will be managed with monitoring by you and your healthcare provider. This monitoring depends on the medicines involved, but may include more frequent assessments to identify if you are experiencing a side effect or if your medicines are working as intended.

For more information on how to keep a list of your medicines, see the medication safety tips.

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