Does this new medicine replace one of my current medicines?

by Michael R. Cohen, R.Ph.

Published Dec. 11, 2013, 5:00 a.m. ET

When your health condition changes, or when new treatments become available, your healthcare providers may recommend changes to your medicines. If this happens, it's important to know whether the changes affect the use of other medicines you are already taking. It's also important to make other healthcare providers aware of the changes. Often, you will be the best person to communicate these changes.

Our sister organization in Canada recently received a report about a patient mistakenly given two different medicines to treat the same problem. The patient's doctor prescribed a new medicine to replace an existing one, but the new medicine was dispensed and eventually taken in addition to the existing one. One of the drugs was Coumadin (warfarin), a blood thinner for preventing blood clots. The patient's family doctor wanted the consumer to start taking a different blood thinner instead, a medicine called dabigatran (Pradaxa).

Two months later, the consumer was planning a cruise vacation and asked the pharmacy to provide refills for several medicines. The pharmacy gave the consumer refills for both the warfarin and the dabigatran, and the consumer took both medicines for 5 days. During the cruise, the consumer noticed that one leg had become dark and swollen. The ship's doctor diagnosed a severe hematoma (a collection of blood under the skin) that was caused by the use of the two blood thinners together. The ship's doctor advised the patient to stop taking the warfarin and the hematoma eventually improved.

Actually, this patient was pretty lucky. The main side effect of each of these drugs alone is excessive bleeding. Taking the two blood thinners together like this is particularly dangerous and easily may have caused severe internal bleeding, like bleeding in the brain if the patient happens to fall and have a head injury. Severe bleeding can be fatal if it isn't treated in time.

Whenever a new medicine is prescribed ask whether it replaces another medicine or changes the way you are supposed to take another medicine. If a doctor or other healthcare provider advises you to stop taking a medicine, make sure your pharmacist knows so it doesn't accidentally get renewed later. Be specific when requesting refills of prescription medicines. Provide both the prescription number and the name for each medicine you require.

Whenever you pick up medicines at the pharmacy, check your prescriptions before you leave. Make sure they have your name on the label and that you received only those medicines you are expecting. It may be helpful to compare the prescription containers you receive from the pharmacy against a list of medicines that you keep. If there are unexpected differences between the containers you receive and your list, speak with a pharmacy staff member.

Finally, know the reason you are taking each of your medicines. Knowing the reason for each medicine can help you understand if you are supposed to be taking more than one medicine for the same reason or if a mistake has been made. Always read any printed material that you receive with your medicine. This often includes information about medicines that may interact with each other, as well as information about possible side effects. If there is anything you do not understand, speak with your pharmacist.