Drug interactions
Ethinyl estradiol-norgestimate + Metronidazole
Severity: Minor
Ethinyl estradiol-norgestimate and Metronidazole: minor 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
Metronidazole has been theorised to reduce oral contraceptive efficacy by disrupting gut flora that recycle estrogen. Pharmacokinetic studies and clinical data do not show a consistent loss of contraceptive protection.
What this interaction means in plain words
Ethinyl estradiol-norgestimate and Metronidazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Ethinyl estradiol-norgestimate belongs to Endocrine; Metronidazole belongs to Anti Parasitic.
Why it happens
Theoretical reduction of enterohepatic recirculation of ethinyl estradiol through alteration of intestinal bacteria; not well established.
What to do
No routine additional contraception is needed; counsel the patient to use backup protection if vomiting or severe diarrhea occurs.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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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 Metronidazole
- Ethanol + Metronidazole Contraindicated
- Metronidazole + Pimozide Contraindicated
- Amiodarone + Metronidazole Major
- Disulfiram + Metronidazole Major
- Ergotamine + Metronidazole Major
- Lomitapide + Metronidazole Major
Frequently asked questions
Can I take Ethinyl estradiol-norgestimate with Metronidazole?
MediHelp rates the interaction as minor. Ethinyl estradiol-norgestimate and Metronidazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Metronidazole has been theorised to reduce oral contraceptive efficacy by disrupting gut flora that recycle estrogen. Pharmacokinetic studies and clinical data do not show a consistent loss of contraceptive protection.
How serious is the interaction between Ethinyl estradiol-norgestimate and Metronidazole?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine additional contraception is needed; counsel the patient to use backup protection if vomiting or severe diarrhea occurs.
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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