Tamoxifen and Liothyronine Interaction

Drug interaction information between Tamoxifen and Liothyronine.

Tamoxifen and Liothyronine have a documented minor interaction in FDA labeling.

FDA drug labeling documents a minor-severity interaction between Tamoxifen and Liothyronine. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.

Drug A

Tamoxifen

Selective Estrogen Receptor Modulator (SERM)

Drug B

Liothyronine

Thyroid Hormone (T3)

How They Interact

Tamoxifen increases the amount of a specific protein in your blood that carries thyroid hormone. This can change the total amount of thyroid medicine measured in your blood tests.

Frequently Asked Questions

What SPL severity band is on file for Tamoxifen + Liothyronine?

Compiled FDA labeling labels this pair minor. That is a source-record field, not an individual medication-combination decision.

Which drug in this pair has the larger labeled-interaction portfolio?

Liothyronine has 17 labeled pairs on file vs Tamoxifen's 10. In the minor band specifically: Tamoxifen has 7 (also Bupropion, Desvenlafaxine, Letrozole, Levothyroxine); Liothyronine has 17 (also Levothyroxine, Sertraline, Furosemide, Propranolol).

What mechanism field is on file for Tamoxifen and Liothyronine?

Tamoxifen increases the amount of a specific protein in your blood that carries thyroid hormone. This can change the total amount of thyroid medicine measured in your blood tests.

Tamoxifen carries more major-labeled pairs than Liothyronine

SPL source-record counts only. This page's band is minor · classes on file: Tamoxifen (Selective Estrogen Receptor Modulator (SERM)); Liothyronine (Thyroid Hormone (T3)).

Tamoxifen has 2 major-labeled pairs vs Liothyronine's 0. This page itself is in the minor band, not the major band.

Tamoxifen

2 major · 1 moderate · 7 minor · 10 total

Liothyronine

0 major · 0 moderate · 17 minor · 17 total

Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.