Taking Tamoxifen (Nolvadex)? Why Paxil and Other Antidepressants Could Pose a Problem

Despite this research, many oncologists continue to prescribe Paxil or Prozac to alleviate hot flashes for their patients on tamoxifen. They may be unaware the troubling research on this question or believe that these studies need further substantiation. In fact, not all experts are in agreement about the possible consequences of taking tamoxifen and SSRIs. For example, researchers presented data at the 2007 San Antonio Symposium on Breast Cancer and concluded the results "do not support the hypothesis that SSRI modify tamoxifen s effectiveness."

The potential of a tamoxifen/SSRI drug interaction continues to be hotly debated in a variety of forums, such as HealthCentral.com's MyBreastCancerNetwork.com and breastcancer.org. "It's a real concern that is being evaluated," says Dr. Marisa C. Weiss, a practicing oncologist who is the founder and president of breastcancer.org. "No one would want to take a medicine that would interfere with the anticancer effect of the tamoxifen."

Dr. Weiss points out that the potential for drug interaction is a key issue for women who have had breast cancer, many of whom are prescribed dozens of medications to take daily. "Whenever you're taking medicines, you want to make sure the side effects are worth the benefits."

For their part, Dr. Goetz and Dr. Flockhart maintain it is best to prescribe patients on tamoxifen medications other than Paxil or Prozac for hot flashes or depression. Both physicians cite the antidepressant Effexor as a drug that does not seem to inhibit the proper breakdown of tamoxifen.

"It works fine on the hot flashes and doesn't affect the enzyme," says Dr. Flockhart, who notes that yet another commonly used antidepressant, Zoloft, has been linked to similar interactions with tamoxifen as Paxil, although to a lesser extent.

In fact, Dr. Goetz is currently conducting a trial to learn more about the potential interactions between tamoxifen and other drugs. "We are going to study this much more comprehensively."