Fulvestrant and Progesterone interaction
Fulvestrant and Progesterone: the Progesterone prescribing label flags this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Progesterone label · effective 2026-06-16
Coronary Heart Disease In women 50 to 59 years of age, the WHI estrogen plus progestin trial reported a relative risk for coronary heart disease (CHD) events (defined as nonfatal MI, silent MI, or CHD death) of 1.34 (95% CI, 0.82, 2.19) for CE/MPA compared placebo, with a risk difference of 5 per 10,000 WYs (23 versus 17).
Breast Cancer Progesterone is contraindicated in women with breast cancer, a history of breast cancer, or estrogen-dependent neoplasia (see CONTRAINDICATIONS).
The Women’s Health Initiative Study In the Women’s Health Initiative (WHI) estrogen plus progestin substudy (daily CE [0.625 mg] plus MPA [2.5 mg] versus placebo), there was a higher relative risk of nonfatal stroke and invasive breast cancer in women greater than 65 years of age (see CLINICAL STUDIES and WARNINGS, Cardiovascular disorders and Malignant neoplasms…
The Women’s Health Initiative (WHI) estrogen plus progestin trial reported increased risks of PE, DVT, stroke, and MI in postmenopausal women (50 to 79 years of age, average age 63.4 years) during 5.6 years of treatment with daily oral conjugated estrogens (CE) [0.625 mg] combined with medroxyprogesterone acetate (MPA) [2.5 mg], relative to placebo.
Therefore, the relevance of the WHI findings regarding adverse cardiovascular events to lower CE plus other MPA doses, other routes of administration, or other estrogen plus progestogen products is not known.
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.