Estradiol and dienogest and Fulvestrant interaction
Estradiol and dienogest and Fulvestrant: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Fulvestrant (CLIGAVYX) label · effective 2026-06-24
Interference of Fulvestrant with Serum Estradiol Immunoassays Due to structural similarity of fulvestrant and estradiol, fulvestrant can interfere with estradiol measurement by immunoassay, resulting in falsely elevated estradiol levels [see Warnings and Precautions (5.4) ] .
Immunoassay Measurement of Serum Estradiol: CLIGAVYX can interfere with estradiol measurement by immunoassay, resulting in falsely elevated estradiol levels.
Immunoassay Measurement of Serum Estradiol Due to structural similarity of fulvestrant and estradiol, fulvestrant can interfere with estradiol measurement by immunoassay, resulting in falsely elevated estradiol levels.
From the Estradiol and dienogest (Natazia) label · effective 2024-06-26
Effects of Other Drugs on Combined Oral Contraceptives Substances diminishing the efficacy of COCs: Dienogest is a substrate of CYP3A4.
Effects of Combined Oral Contraceptives on Other Drugs COCs containing ethinyl estradiol may inhibit the metabolism of other compounds.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
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.