Drug interactions
Ethinyl estradiol-drospirenone + Tamoxifen
Severity: Major
Ethinyl estradiol-drospirenone and Tamoxifen: major interaction.
Last updated Sources: UK SmPC
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Tamoxifen is an antiestrogen used in hormone-receptor-positive breast cancer, and estrogen-containing contraceptives are generally contraindicated in patients with breast cancer. Hormonal contraception also opposes the therapeutic intent of tamoxifen and may stimulate hormone-sensitive tumor growth. Tamoxifen is also not a reliable contraceptive and is teratogenic, so effective non-hormonal contraception is needed.
What this interaction means in plain words
Ethinyl estradiol-drospirenone and Tamoxifen can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Ethinyl estradiol-drospirenone belongs to Endocrine; Tamoxifen belongs to Endocrine.
Why it happens
Pharmacodynamic antagonism: exogenous estrogen opposes tamoxifen's antiestrogenic action at the estrogen receptor.
What to do
Avoid combined hormonal contraceptives in women taking tamoxifen for breast cancer; use non-hormonal methods such as a copper IUD or barrier methods. If tamoxifen is used for risk reduction, review the contraceptive choice with the oncology team.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Ethinyl estradiol-drospirenone
- Ethinyl estradiol-drospirenone + Fezolinetant Contraindicated
- Ethinyl estradiol-drospirenone + Ombitasvir / paritaprevir / ritonavir Contraindicated
- Ethinyl estradiol-drospirenone + Ombitasvir / paritaprevir / ritonavir and dasabuvir Contraindicated
- Ethinyl estradiol-drospirenone + Tranexamic acid Contraindicated
- Aminocaproic acid + Ethinyl estradiol-drospirenone Major
- Amobarbital + Ethinyl estradiol-drospirenone Major
Other interactions of Tamoxifen
- Amiodarone + Tamoxifen Major
- Anastrozole + Tamoxifen Major
- Bupropion + Tamoxifen Major
- Carbamazepine + Tamoxifen Major
- Cinacalcet + Tamoxifen Major
- Dacomitinib + Tamoxifen Major
Frequently asked questions
Can I take Ethinyl estradiol-drospirenone with Tamoxifen?
MediHelp rates the interaction as major. Ethinyl estradiol-drospirenone and Tamoxifen can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Tamoxifen is an antiestrogen used in hormone-receptor-positive breast cancer, and estrogen-containing contraceptives are generally contraindicated in patients with breast cancer. Hormonal contraception also opposes the therapeutic intent of tamoxifen and may stimulate hormone-sensitive tumor growth. Tamoxifen is also not a reliable contraceptive and is teratogenic, so effective non-hormonal contraception is needed.
How serious is the interaction between Ethinyl estradiol-drospirenone and Tamoxifen?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid combined hormonal contraceptives in women taking tamoxifen for breast cancer; use non-hormonal methods such as a copper IUD or barrier methods. If tamoxifen is used for risk reduction, review the contraceptive choice with the oncology team.
What other medicines interact with Ethinyl estradiol-drospirenone?
MediHelp also lists interactions of Ethinyl estradiol-drospirenone with, for example, Fezolinetant, Ombitasvir / paritaprevir / ritonavir, Ombitasvir / paritaprevir / ritonavir and dasabuvir. The full list is on the Ethinyl estradiol-drospirenone page.
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