Drugs to Avoid for Women Taking Tamoxifen

Blossom Paravattil, Megan Cole, and Danielle Shapiro, MD, MPH, Cancer Prevention and Treatment Fund

The female hormone estrogen makes most cancer tumor cells grow and multiply. The drug tamoxifen was developed to block estrogen and therefore stop that growth, to help treat, prevent, and stop the recurrence of most breast cancer.  Breast cancer that is sensitive to estrogen is called “estrogen receptor-positive breast cancer.”

For tamoxifen to do its job, it needs to be broken down in the body by a key protein known as CYP2D6.  Unfortunately, many common medicines can block or slow down CYP2D6, and that would make tamoxifen less effective.

Certain medications used to treat depression should be avoided by women taking tamoxifen. The antidepressants paroxetine (Paxil) and fluoxetine (Prozac) have been found to increase women’s risk of dying of cancer if they are taking tamoxifen. Women who are on these medications should talk to their doctors about switching to other medicines that don’t affect how tamoxifen works.

The table below shows a list of drugs to avoid and alternative drugs that can be taken instead.


Classes of drugs Drugs that are likely to interfere with tamoxifen

Alternative drugs that should be safe to take with tamoxifen

Antidepressants (SSRI/SNRIs) Paxil, Prozac, Wellbutrin, and Cymbalta Effexor, Pristiq, Edronax, Lexapro, and Remeron
Antipsychotics Mellaril, Trilafon, and Orap Navane, Clozaril, Zyprexa, Geodon, and Seroquel
Cardiac Drugs Cardioquin and Ticlid Cardizem
Allergy medications Benadryl (diphenhydramine), Unisom (doxylamine), Dimetapp (Brompheniramine), Tagamet (cimetidine) Zyrtec (cetirizine), Claritin (Loratadine), Fexofenadine (Allegra), Ranitidine (Zantac)
Medications for Infectious Diseases Seldane and Cardioquin Crixivan, Invirase, Viracept, Rescriptor, Viramune, and Sustiva

The Bottom Line

If you are taking tamoxifen, talk to your doctor about any medications  that you are taking (including over-the-counter products, such as cold and allergy medications) to be sure that they don’t interfere with tamoxifen.

All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.


  1. Zosia Chustecka. Medscape News. Drugs to Avoid in Women Taking Tamoxifen. May 05, 2010. Accessed December 2017 Available online: https://www.medscape.com/viewarticle/721306