Drug interactions
Estradiol + Ritonavir
Severity: Moderate
Estradiol and Ritonavir: moderate interaction.
Last updated
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
Ritonavir has complex effects on estrogen exposure. Short-term it inhibits CYP3A4, which may raise estradiol levels, while longer use induces other pathways such as glucuronidation, which may lower levels. The net effect is unpredictable.
What this interaction means in plain words
Estradiol and Ritonavir can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Estradiol belongs to Endocrine; Ritonavir belongs to Anti Virals.
Why it happens
Ritonavir inhibits CYP3A4 and P-glycoprotein but may also induce glucuronidation and other enzymes.
What to do
Monitor for estrogenic adverse effects such as breast tenderness, nausea and bleeding, as well as for loss of effect. Adjust the estradiol dose based on response.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Estradiol
- Anastrozole + Estradiol Contraindicated
- Estradiol + Fezolinetant Contraindicated
- Estradiol + Ospemifene Contraindicated
- Antithrombin alfa + Estradiol Major
- Antithrombin iii + Estradiol Major
- Estradiol + Exemestane Major
Other interactions of Ritonavir
- Alfuzosin + Ritonavir Contraindicated
- Amiodarone + Ritonavir Contraindicated
- Avanafil + Ritonavir Contraindicated
- Colchicine + Ritonavir Contraindicated
- Dronedarone + Ritonavir Contraindicated
- Eletriptan + Ritonavir Contraindicated
Frequently asked questions
Can I take Estradiol with Ritonavir?
MediHelp rates the interaction as moderate. Estradiol and Ritonavir can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Ritonavir has complex effects on estrogen exposure. Short-term it inhibits CYP3A4, which may raise estradiol levels, while longer use induces other pathways such as glucuronidation, which may lower levels. The net effect is unpredictable.
How serious is the interaction between Estradiol and Ritonavir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for estrogenic adverse effects such as breast tenderness, nausea and bleeding, as well as for loss of effect. Adjust the estradiol dose based on response.
What other medicines interact with Estradiol?
MediHelp also lists interactions of Estradiol with, for example, Anastrozole, Fezolinetant, Ospemifene. The full list is on the Estradiol page.
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