Gestodene and Felbamate: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Felbamate
Gestodene
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Decreased contraceptive effectiveness and intermenstrual bleeding
Interaction Deep Dive
Felbamate has been shown to decrease the area under the plasma concentration time curve of gestodene and ethinyl estradiol in a low-dose combination contraceptive product1.
Why it happens (mechanism)
Increased metabolism of progestin and estrogen
Literature reports
1 report — tap to read
a) The effect of felbamate on the pharmacokinetics of a low-dose combination oral contraceptive was studied in healthy adult female volunteers 1. All volunteers were stabilized on a combination oral contraceptive product containing 30 mcg of ethinyl estradiol and 75 mcg gestodene. Subjects were then randomized to receive either placebo (n=8) or felbamate 2400 mg daily, from day 15 of one cycle (month) until day 14 of the next cycle. The area under the concentration-time curve (AUC) was significantly decreased for gestodene by 42%. Although none of the subjects had hormonal indications of ovulation, one subject experienced intermenstrual bleeding while taking felbamate. The AUC for ethinyl estradiol was decreased significantly by 13%, although this reduction was probably not clinically significant.
Common questions
Can I take Gestodene and Felbamate together?
Decreased contraceptive effectiveness and intermenstrual bleeding Always confirm with your pharmacist or prescriber before making any change.
How serious is the Gestodene and Felbamate interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Gestodene or Felbamate need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Saano V, Glue P, Banfield CR, et al: Effects of felbamate on the pharmacokinetics of a low-dose combination oral contraceptive. Clin Pharmacol Ther 1995; 58:523-531. PubMed
Keep reading about Felbamate
Keep reading about Gestodene
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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