Mouth Sores

QUESTION: I am presently taking tamoxifen and had my last CMF chemo treatment eight months ago. During the chemo I did get mouth sores. In the last few months, I've had some mouth sores again. They did heal completely, but I've developed another one. Are mouth sores a side effect of tamoxifen? Is there anything I can do to prevent these from occurring? Should I be contacting one of my doctors (family, gynecologist, oncologist, or dentist)? Thanks in advance for any info you can provide.

ANSWER: I am sorry that you have been suffering from mouth sores. Various things can cause or contribute to them, including the 5FU chemotherapy that's part of CMF (it's the "F"). After the chemo gets out of your system and your blood counts return to close to normal, the mouth sores usually go away. There are exceptions to this generalization. Sometimes, for example, people get mouth sores from a reactivation of the herpes virus from a prior chicken pox infection (even as long ago as childhood). This usually is intermittent, like what you've described, and is not uncommon in all people (not just people who've had cancer treatment). Tamoxifen is not known to be associated with mouth sores. We encourage you to go your doctor to evaluate your situation further. Hopefully he or she can sort out the cause of the problem and give you something that will help relieve it.

—Marisa Weiss, M.D.