PharmD Info

Tamoxifen remains active for up to two weeks after the previous dose. However, it can take up to three months to fully flush out of your system.

Tamoxifen citrate is an extremely successful breast cancer treatment. It may dramatically reduce the chance of recurrent or aggressive breast cancer. Tamoxifen, a medicine used to treat and prevent breast cancer, can remain in the body for a long time after therapy ends.

Here's a breakdown of how long tamoxifen stays in your system:

The active form of tamoxifen, endoxifen, has a half-life of about 7 days. This means that the body takes around 7 days to clear half of the drug's levels. However, tamoxifen and its metabolites can be identified in the body for several weeks after treatment is discontinued. According to studies, therapeutic levels of tamoxifen can linger for up to 4-6 weeks following the final dose. Tamoxifen normally takes about 3 months (or 5 half-lives) to be entirely removed from the body. During this time, the drug's effects may progressively fade, although residual effects may remain. The exact period varies from person to person, based on age, metabolism, and general health. You must follow your healthcare provider's instructions for the duration of tamoxifen treatment, as well as any necessary precautions or follow-up care after discontinuing the prescription.