Mircette 28 Day Drug Interactions: What to Avoid and What to Tell Your Doctor

Mircette 28 Day (desogestrel/ethinyl estradiol) can interact with several medications and supplements. Some interactions reduce the pill's effectiveness — potentially leading to unintended pregnancy. Others increase the hormone levels in your blood, raising the risk of side effects. Knowing which drugs to watch out for — and what to tell your prescriber — is essential for safe and effective use.

Drugs That Make Mircette Less Effective (Major Interactions)

These medications speed up how quickly your body breaks down the hormones in Mircette, reducing blood levels of desogestrel and ethinyl estradiol and potentially allowing ovulation:

Rifampin (Rifadin) — Used for tuberculosis. One of the most potent inducers of drug metabolism. Can dramatically reduce contraceptive hormone levels. Use backup contraception and consider an alternative method while on rifampin.

Carbamazepine (Tegretol) — Antiepileptic and mood stabilizer. Induces liver enzymes that metabolize estrogen and progestins. Significantly reduces contraceptive effectiveness.

Phenytoin (Dilantin) — Antiepileptic drug. Like carbamazepine, it induces hepatic enzymes and reduces hormone levels.

Phenobarbital — Antiepileptic drug and sedative. Enzyme inducer that reduces COC effectiveness.

Topiramate (Topamax) — Antiepileptic and migraine preventive. At doses above 200mg/day, may reduce contraceptive effectiveness.

Oxcarbazepine (Trileptal) — Antiepileptic drug. Enzyme inducer similar to carbamazepine.

Griseofulvin — Antifungal used for skin, hair, and nail fungal infections. May reduce COC effectiveness.

HIV Medications and Hepatitis C Treatments

HIV protease inhibitors and non-nucleoside reverse transcriptase inhibitors (NNRTIs) — Some HIV antiretroviral drugs can either increase or decrease ethinyl estradiol levels. The direction of interaction depends on the specific drug. Always inform your HIV specialist that you're taking oral contraceptives.

Ombitasvir/paritaprevir/ritonavir (Viekira Pak) — Used for Hepatitis C. Causes significant ALT elevations (liver enzyme increases) in women taking ethinyl estradiol-containing contraceptives. Mircette must be discontinued before starting this hepatitis C regimen. It can be restarted approximately 2 weeks after completing treatment.

Supplements and Natural Products That Interact

St. John's Wort (Hypericum perforatum) — Popular herbal supplement for mood. A strong inducer of liver enzymes that can significantly reduce contraceptive hormone levels. There are documented cases of unintended pregnancy in women taking St. John's Wort with oral contraceptives. Avoid concurrent use or use backup contraception.

Medications Affected by Mircette (Bidirectional Interactions)

Lamotrigine (Lamictal) — Antiepileptic used for bipolar disorder and seizures. Estrogen in birth control pills can significantly reduce lamotrigine blood levels, potentially reducing seizure control. If you're on lamotrigine, your neurologist should monitor levels closely when starting or stopping hormonal contraceptives.

Cyclosporine — Immunosuppressant. Ethinyl estradiol may increase cyclosporine levels, raising the risk of toxicity. Inform your transplant team if starting Mircette.

Theophylline — Used for asthma and COPD. Ethinyl estradiol may decrease theophylline clearance, potentially raising theophylline levels.

What About Antibiotics?

For decades, women were advised to use backup contraception with all antibiotics. Current guidance has changed: most common antibiotics (amoxicillin, doxycycline, azithromycin, trimethoprim/sulfamethoxazole) do not meaningfully reduce contraceptive effectiveness. The one clear exception is rifampin (rifampicin), which remains a major concern. If you are prescribed any antibiotic, it's still a good idea to mention your birth control to your prescriber and ask whether backup contraception is needed.

What to Tell Your Doctor

Before starting Mircette 28 Day, give your prescriber a complete list of:

All prescription medications, including psychiatric, neurological, and infectious disease drugs

All over-the-counter medications and supplements — especially St. John's Wort

Any herbal supplements, vitamins, or natural remedies

Any changes to your medication list while on Mircette

For more on monitoring side effects while on Mircette, see our Mircette side effects guide. For a full overview of the medication, visit What Is Mircette 28 Day?.