Certain blood pressure medication can interact with pretty common antibiotics, and they can cause some serious reactions of severely low blood pressure.  A large study from Canada including 999,000 patients form Ontario from 1994-2009 found some shocking results.

The patients were all 66 year old and up and were on calcium channel blockers ( a type of blood pressure medication that works by disrupting calcium going through the various calcium channels that can affect excitable muscles like the heart and blood vessels.)  Some examples of calcium channel blockers are: Amlodipine (Norvasc), Nifedipine (Procardia, Adalat), and Diltiazem (Cardizem). In the study they found that 7,100 patients were hospitalized for severe drops in blood pressure and of those 131 had been on antibiotics the week before.

Now it isn’t all antibiotics, its a certain group known as macrolides, which are the most highly prescribed antibiotics in the US, and are drugs such as: Erythromycin (E-mycin), clarithromycin (Biaxin), and Azithromycin (Zithromax). And they are pretty broad band gram positive bacteria (including streptococcus and haemophilus influenzae) and they are a good alternative for those allergic to penicllin.  With Erthromyin and calcium channel blockers there was a six fold increase risk in severe low blood pressure and with clarithromycin there was a four fold increase.  There was no interaction found between Azithromycin and calcium channel blockers.

This drop in blood pressure for older adults can be devastating due to the fact that they can get dizzy fall and break bones OR have such os blood pressure that they are no longer getting adequate blood flow to their major organs and have lack of oxygen and cell death (usually the kidneys are the first to be affected).  Younger patients may be able to tolerate these changes in blood pressure with less of an overall effect, but the results of the studies still suggest that if you are on a calcium channel blocker and require a broad band antibiotic, Azithromycin is the best choice.

There have been no interactions noted between beta blockers (metoprolol/Lopressor) or ACE inhibitors (Lisinopril/Zestril) which are other common blood pressure medications.  So, please discuss your risk if you are on a blood pressure medication with your HCP before starting an antibiotic regimen.

Yours in Good Health!
B