Drug interactions
Carbamazepine + Ethinyl estradiol-norgestimate
Severity: Major
Carbamazepine and Ethinyl estradiol-norgestimate: 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 is a strong enzyme inducer that lowers ethinyl estradiol and progestin levels, causing breakthrough bleeding and contraceptive failure. Carbamazepine is also teratogenic, so reliable contraception is essential.
What this interaction means in plain words
Carbamazepine and Ethinyl estradiol-norgestimate 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 belongs to Central Nervous System; Ethinyl estradiol-norgestimate belongs to Endocrine.
Why it happens
Induction of CYP3A4 and other hepatic enzymes accelerates clearance of the contraceptive hormones.
What to do
Use a non-hormonal or non-affected method such as a copper IUD, levonorgestrel IUD or medroxyprogesterone injection. Do not rely on combined oral contraceptives.
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-norgestimate
- Ethinyl estradiol-norgestimate + Fezolinetant Contraindicated
- Ethinyl estradiol-norgestimate + Ombitasvir / paritaprevir / ritonavir and dasabuvir Contraindicated
- Ethinyl estradiol-norgestimate + Tranexamic acid Contraindicated
- Aminocaproic acid + Ethinyl estradiol-norgestimate Major
- Amobarbital + Ethinyl estradiol-norgestimate Major
- Anastrozole + Ethinyl estradiol-norgestimate Major
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 Ethinyl estradiol-norgestimate?
MediHelp rates the interaction as major. Carbamazepine and Ethinyl estradiol-norgestimate 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 is a strong enzyme inducer that lowers ethinyl estradiol and progestin levels, causing breakthrough bleeding and contraceptive failure. Carbamazepine is also teratogenic, so reliable contraception is essential.
How serious is the interaction between Carbamazepine and Ethinyl estradiol-norgestimate?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use a non-hormonal or non-affected method such as a copper IUD, levonorgestrel IUD or medroxyprogesterone injection. Do not rely on combined oral contraceptives.
What other medicines interact with Ethinyl estradiol-norgestimate?
MediHelp also lists interactions of Ethinyl estradiol-norgestimate with, for example, Fezolinetant, Ombitasvir / paritaprevir / ritonavir and dasabuvir, Tranexamic acid. The full list is on the Ethinyl estradiol-norgestimate page.
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