Rivelsa 91 Day Drug Interactions: What to Avoid and What to Tell Your Doctor

Like all combination oral contraceptives, Rivelsa 91 Day can interact with other medications, herbal supplements, and certain foods. Some interactions reduce its effectiveness at preventing pregnancy; others can cause serious side effects. Here's a comprehensive guide to Rivelsa drug interactions and what to discuss with your healthcare provider.

Drugs That Reduce Rivelsa's Effectiveness (CYP3A4 Inducers)

The most clinically important drug interactions with Rivelsa are medications that activate liver enzymes (particularly CYP3A4) that break down the hormones more quickly than normal. This reduces the hormone levels in your blood and can make Rivelsa less effective at preventing pregnancy. If you take any of these medications, discuss the interaction with your provider and use backup contraception (condoms) while on them:

Rifampin (Rifampicin): An antibiotic used for tuberculosis and some other bacterial infections. One of the most potent enzyme inducers — significantly reduces COC effectiveness. Use a non-hormonal contraceptive while taking rifampin.

Anticonvulsants/Anti-seizure medications: Including phenytoin (Dilantin), carbamazepine (Tegretol), phenobarbital, primidone, topiramate (Topamax), and oxcarbazepine (Trileptal). These are all significant CYP3A4 inducers. Patients on these medications should use additional contraception or consider a non-hormonal method.

St. John's Wort (Hypericum perforatum): This popular herbal supplement for depression is a potent CYP3A4 inducer. It can significantly reduce ethinyl estradiol levels. Do not take St. John's Wort while on Rivelsa without discussing with your provider.

Some HIV medications: Including lopinavir/ritonavir, nelfinavir, nevirapine, and efavirenz. Some HIV protease inhibitors and non-nucleoside reverse transcriptase inhibitors can significantly alter hormone levels.

CONTRAINDICATED Drug Combination: Hepatitis C Medications

Rivelsa is contraindicated with the Hepatitis C drug combination ombitasvir/paritaprevir/ritonavir (Technivie, Viekira Pak), with or without dasabuvir. This combination has been shown to cause significant increases in liver enzyme (ALT) levels when taken with ethinyl estradiol-containing medications. You must stop Rivelsa before starting this HCV regimen and can restart approximately 2 weeks after completing the course. The same interaction applies to glecaprevir/pibrentasvir (Mavyret).

Drugs That Can Increase Rivelsa Hormone Levels (CYP3A4 Inhibitors)

Some drugs inhibit the enzymes that break down Rivelsa's hormones, leading to higher than normal hormone levels in your blood. While this doesn't reduce contraceptive effectiveness, it may increase side effects:

Antifungals: Itraconazole, voriconazole, fluconazole, and ketoconazole can increase estrogen/progestin exposure.

Grapefruit and grapefruit juice: A moderate CYP3A4 inhibitor. Regular large consumption of grapefruit may increase estrogen levels modestly.

Ascorbic acid (Vitamin C) and acetaminophen: High doses may increase ethinyl estradiol exposure by inhibiting conjugation. This is generally not clinically significant at normal doses.

Drug Interactions That Affect Other Medications (Rivelsa Affecting Other Drugs)

Rivelsa can also affect how other drugs work in your body:

Lamotrigine (Lamictal): COCs significantly increase the metabolism of lamotrigine, reducing its blood levels and potentially reducing seizure control. Patients on lamotrigine should work closely with their neurologist and OB/GYN.

Thyroid hormone: COCs may increase thyroid-binding globulin levels. Patients on thyroid replacement therapy may need dose adjustments.

Cyclosporine: COCs may increase cyclosporine levels, increasing the risk of cyclosporine toxicity.

What About Regular Antibiotics?

There is a common myth that all antibiotics reduce birth control effectiveness. Current evidence does not support this for most antibiotics. The exception is rifampin (used for TB), which is a potent enzyme inducer. For standard antibiotics like amoxicillin, doxycycline, or azithromycin, the interaction is not clinically significant. However, if you are ill and vomiting or have significant diarrhea while on antibiotics, absorption of your pill may be affected — treat any vomiting within 3-4 hours of taking Rivelsa as a missed dose.

Always Tell Your Provider About Every Medication You Take

Before starting Rivelsa, give your prescriber a complete list of all prescription drugs, over-the-counter medications, vitamins, and herbal supplements you take. This includes things you might not think of as 'real medicine' like St. John's Wort or high-dose vitamin C. Also read our guide on Rivelsa side effects and what Rivelsa is used for.