Drug interactions
Carbamazepine + Ethinylestradiol
Severity: Major
Carbamazepine and Ethinylestradiol: major interaction.
Last updated Sources: US FDA label
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
Carbamazepine markedly lowers ethinylestradiol exposure, so hormonal contraceptives may fail and unintended pregnancy can occur. Breakthrough bleeding is also common. Ethinylestradiol may modestly affect carbamazepine levels.
What this interaction means in plain words
Carbamazepine and Ethinylestradiol 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.
Why it happens
Carbamazepine induces CYP3A4 and other hepatic enzymes, accelerating metabolism of ethinylestradiol and progestins.
What to do
Advise a non-hormonal method such as a copper IUD or levonorgestrel IUD, or add a barrier method. Combined pills are not reliable with carbamazepine.
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 Carbamazepine
- Artemether / lumefantrine + Carbamazepine Contraindicated
- Cabotegravir + Carbamazepine Contraindicated
- Carbamazepine + Delamanid Contraindicated
- Carbamazepine + Dienogest / estradiol valerate Contraindicated
- Carbamazepine + Doravirine Contraindicated
- Carbamazepine + Elbasvir / grazoprevir Contraindicated
Frequently asked questions
Can I take Carbamazepine with Ethinylestradiol?
MediHelp rates the interaction as major. Carbamazepine and Ethinylestradiol 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. Carbamazepine markedly lowers ethinylestradiol exposure, so hormonal contraceptives may fail and unintended pregnancy can occur. Breakthrough bleeding is also common. Ethinylestradiol may modestly affect carbamazepine levels.
How serious is the interaction between Carbamazepine and Ethinylestradiol?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Advise a non-hormonal method such as a copper IUD or levonorgestrel IUD, or add a barrier method. Combined pills are not reliable with carbamazepine.
What other medicines interact with Carbamazepine?
MediHelp also lists interactions of Carbamazepine with, for example, Artemether / lumefantrine, Cabotegravir, Delamanid. The full list is on the Carbamazepine page.
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