Ethinyl Estradiol/Levonorgestrel Drug Interactions: What to Avoid and What to Tell Your Doctor

Ethinyl estradiol/levonorgestrel (EE/LNG) has significant drug interactions — some that reduce its contraceptive effectiveness (potentially leading to unintended pregnancy) and others that increase the risk of serious side effects. Before starting, stopping, or changing any medication while taking EE/LNG, it's critical to discuss it with your prescriber or pharmacist.

This guide covers the most clinically important interactions — including contraindicated combinations, medications that reduce effectiveness, and dietary interactions you should know about.

Contraindicated Combinations (Do Not Use Together)

These combinations are contraindicated — meaning EE/LNG should not be used at the same time:

Ombitasvir/paritaprevir/ritonavir ± dasabuvir (Viekira Pak, Technivie): Used for hepatitis C. Coadministration causes significant ALT elevations (>5x ULN, sometimes >20x ULN). Discontinue EE/LNG before starting this regimen and restart 2 weeks after completion.

Fezolinetant (Veozah): Used for menopause hot flashes. Ethinyl estradiol inhibits CYP1A2 metabolism, significantly increasing fezolinetant blood levels. Contraindicated.

Tranexamic acid (Lysteda) oral: Used for heavy periods. Combination with EE/LNG significantly increases thrombotic risk. Contraindicated.

Drugs That Reduce EE/LNG Effectiveness (Enzyme Inducers)

These medications speed up the liver enzymes (primarily CYP3A4) that metabolize ethinyl estradiol and levonorgestrel, reducing their blood levels and potentially allowing ovulation. If you take any of these, use backup contraception (condoms) throughout your treatment and for at least 28 days after stopping:

Rifampin (Rifadin): Antibiotic used for tuberculosis. The most potent enzyme inducer known to reduce COC effectiveness. Use alternative contraception during and 4 weeks after rifampin.

Anti-seizure medications (enzyme-inducing AEDs): Carbamazepine (Tegretol), phenytoin (Dilantin), phenobarbital, primidone, topiramate (Topamax at doses >200 mg/day), and oxcarbazepine. If you take these, discuss alternative or additional contraception with your neurologist and gynecologist.

HIV medications (protease inhibitors and NNRTIs): Ritonavir, lopinavir, efavirenz, nelfinavir, and others may reduce EE/LNG levels. Some HIV medications increase hormone levels instead. Tell your HIV specialist about your birth control.

Aprepitant (Emend): Anti-nausea drug used with chemotherapy. Can reduce EE levels — use backup contraception during and 28 days after use.

Bosentan (Tracleer): Used for pulmonary arterial hypertension. Induces CYP3A4 and reduces EE effectiveness.

Belzutifan (Welireg): Cancer treatment. Can cause fetal harm and reduces EE effectiveness. Use effective non-hormonal contraception.

Herbal Products That Reduce EE/LNG Effectiveness

St. John's Wort (Hypericum perforatum): A widely used herbal supplement for depression and anxiety. St. John's Wort is a potent CYP3A4 inducer and has been documented to cause breakthrough bleeding and contraceptive failure in women taking combination oral contraceptives. Do not combine with EE/LNG.

Drugs That Increase EE Levels

Some drugs inhibit the enzymes that break down ethinyl estradiol, causing EE levels to rise. This can increase EE-related side effects and risks:

Atorvastatin and rosuvastatin (statins): Increase EE AUC by approximately 20-25%. May require discussion with your prescriber about estrogen dose.

Azole antifungals (itraconazole, fluconazole, ketoconazole, voriconazole): CYP3A4 inhibitors that increase systemic EE exposure. Usually not a clinically significant concern for short-course antifungal treatment.

Ascorbic acid (Vitamin C) and acetaminophen: High doses may modestly increase EE bioavailability. Not generally clinically significant at normal supplementation doses.

Food Interactions

Grapefruit juice: Inhibits CYP3A4 in the intestinal wall, increasing ethinyl estradiol blood levels. While not contraindicated, patients taking EE/LNG should be aware of this and discuss with their provider if they consume grapefruit regularly.

What About Antibiotics?

A long-standing concern has been whether broad-spectrum antibiotics (like amoxicillin, doxycycline, or azithromycin) reduce birth control effectiveness. The current scientific consensus — supported by the FDA and ACOG — is that non-enzyme-inducing antibiotics do NOT meaningfully reduce EE/LNG effectiveness. The exception is rifampin (a tuberculosis antibiotic), which does significantly reduce effectiveness. You do NOT need backup contraception when taking a standard antibiotic for an infection, unless your doctor specifically tells you otherwise.

Key Takeaways for Patients

Always tell every prescriber and pharmacist that you are on birth control pills

Avoid St. John's Wort while taking EE/LNG

Use backup contraception if starting enzyme-inducing medications (rifampin, certain anti-seizure drugs)

Do not start the hepatitis C drug ombitasvir/paritaprevir/ritonavir while on EE/LNG — switch to a non-estrogen method first

Regular antibiotics (amoxicillin, doxycycline, etc.) do NOT require backup contraception with EE/LNG

For more on side effects, see our complete side effects guide. To understand why enzyme inducers matter, read how EE/LNG works at the hormonal level.