What to Avoid When Taking Mavyret: Key Interactions

Mavyret (glecaprevir/pibrentasvir) is one of the most widely prescribed hepatitis C treatments, but several medications, supplements, and health conditions can either undermine its effectiveness or cause serious harm when combined with it. The interactions range from drugs that slash Mavyret’s blood levels so low it cannot clear the virus, to combinations that spike liver enzymes to dangerous levels. Some of these are hard contraindications that your prescriber will screen for in advance, while others are subtler shifts that you and your medical team need to watch for during the eight-to-sixteen-week treatment course.

Drugs That Are Strictly Contraindicated

A handful of medications should never be taken alongside Mavyret because the interaction is either dangerous or renders the antiviral useless. The most important are rifampin (used for tuberculosis and some other infections) and carbamazepine (a seizure and mood-stabilizer medication). Both are potent enzyme inducers, meaning they ramp up your body’s machinery for breaking down and flushing out other drugs. When researchers gave healthy volunteers Mavyret together with multiple doses of rifampin or carbamazepine, the blood levels of both glecaprevir and pibrentasvir dropped dramatically, likely because both inducers accelerated the drug-pumping protein P-glycoprotein in the gut wall.¹ Another inducer, efavirenz (an older HIV drug), has a similar effect and is also flagged as a problem.² If Mavyret levels fall too low, the virus is not suppressed and you risk treatment failure or developing drug-resistant hepatitis C strains.

Atazanavir, an HIV protease inhibitor, sits in a different category but is equally off-limits. Rather than lowering Mavyret’s levels, atazanavir pushes them higher. In a healthy-volunteer study, the combination caused elevated liver enzymes (ALT), the same kind of liver-stress signal that leads clinicians to stop treatment. Because of that ALT signal, atazanavir is specifically contraindicated with Mavyret, not just discouraged.³

Why Ethinyl Estradiol Is a Problem

If you use a hormonal contraceptive that contains ethinyl estradiol, you will need to switch before starting Mavyret. This includes most combined oral contraceptive pills, the vaginal ring, and the contraceptive patch. The reason is not that the birth control stops working or that Mavyret becomes less effective; the concern is liver injury. In an early clinical study, when healthy women took Mavyret alongside an oral contraceptive containing 35 micrograms of ethinyl estradiol, two out of twelve developed significant ALT elevations after just eleven days.⁴ In combined data from larger phase 2 and phase 3 trials, six additional patients on Mavyret plus ethinyl estradiol showed abnormal liver tests.⁵

The exact mechanism behind the liver-enzyme spike remains unknown, which is part of why the labeling takes a conservative approach: any ethinyl estradiol-containing product, including intravaginal formulations, is flagged as not recommended during Mavyret treatment. Progestin-only methods (the mini-pill, hormonal IUDs, the implant, the injection) are not affected and remain safe alternatives for the duration of your treatment course.

HIV Medications and Mavyret

Hepatitis C and HIV frequently overlap, so drug interactions between Mavyret and antiretroviral regimens get a lot of clinical attention. The picture is mixed rather than uniformly dangerous. Mavyret’s blood levels rise when it is taken with ritonavir-boosted protease inhibitors like darunavir/ritonavir or lopinavir/ritonavir. The mechanism involves inhibition of transport proteins and enzymes that normally clear glecaprevir from the body. While the higher exposure is not linked to a specific dose-limiting side effect, the limited real-world experience with these combinations in people coinfected with both viruses has led guidelines to recommend against using boosted darunavir or lopinavir/ritonavir with Mavyret.³

There is an important exception. The integrase inhibitor elvitegravir combined with cobicistat, emtricitabine, and tenofovir alafenamide (sold as Genvoya) does increase Mavyret levels somewhat, but the increases were not considered clinically meaningful after exposure-safety analysis. So that regimen can typically be used alongside Mavyret. If you are on HIV treatment and need hepatitis C therapy, your providers will review your specific antiretroviral combination; in many cases switching to a compatible HIV regimen for the duration of Mavyret is straightforward.

Immunosuppressants After Organ Transplant

Tacrolimus and cyclosporine are the two pillars of anti-rejection therapy for transplant recipients, and both interact with Mavyret, but in very different ways. Tacrolimus is the simpler story: it does not meaningfully change Mavyret’s levels, but Mavyret raises tacrolimus exposure by about 45%. That means your transplant team will likely need to monitor tacrolimus blood levels more frequently during treatment and adjust the dose downward to keep you in the safe range.⁶

Cyclosporine is the trickier situation. At a low dose of 100 milligrams, cyclosporine had a modest effect on Mavyret, raising glecaprevir exposure by no more than about a third. But at a dose of 400 milligrams, cyclosporine increased glecaprevir exposure by roughly fivefold and pibrentasvir by nearly double.⁶ That fivefold jump raises real safety concerns, particularly for liver toxicity. For this reason, Mavyret’s label allows coadministration with cyclosporine only at doses of 100 milligrams per day or less. Patients on higher cyclosporine doses generally need an alternative hepatitis C regimen or a supervised switch in their immunosuppression before starting Mavyret.

Acid-Reducing Medications

Proton pump inhibitors (PPIs) like omeprazole and pantoprazole, along with H2 blockers and antacids, are among the most commonly used drugs worldwide, so the question of whether they interfere with Mavyret comes up constantly. The good news is that the interaction, while real, does not appear to compromise cure rates. In a large pooled analysis of clinical trial patients, about 97% of those using acid-reducing agents achieved a sustained virologic response, compared with roughly 97.5% of those not using them, a difference that was not statistically significant. Even among patients on high-dose PPIs, no virologic failures were observed.⁷

That said, the pharmacokinetic data show that glecaprevir’s blood levels dropped by about 41% in patients taking a high-dose PPI, even though pibrentasvir was unaffected.⁷ Because of this pharmacokinetic dip, the prescribing information advises taking PPIs at the same time as or within a few hours of Mavyret rather than spreading them throughout the day, and capping PPI doses at the equivalent of omeprazole 20 milligrams. If you take over-the-counter heartburn medication, you do not need to stop it, but let your prescriber know so they can confirm the timing and dose are appropriate.

Severe Liver Disease

This one catches some patients by surprise. Mavyret is a hepatitis C drug, so you might assume it is safe for anyone whose liver is affected by the virus. But Mavyret contains a protease inhibitor (glecaprevir), and protease inhibitors are processed heavily by the liver. In patients with moderate-to-severe cirrhosis, classified as Child-Pugh B or C, the risk of hepatic decompensation, where the liver effectively gives out under the added metabolic load, is significant enough that Mavyret is contraindicated.⁸ Patients with well-compensated cirrhosis (Child-Pugh A) can safely use Mavyret, often with an extended treatment course. But if your liver function has deteriorated beyond that threshold, your hepatologist will steer you toward a non-protease-inhibitor-based regimen instead.

Hepatitis B Reactivation

In 2016, the FDA added a black-box warning to all direct-acting antiviral therapies for hepatitis C, including Mavyret, about the risk of hepatitis B virus (HBV) reactivation. The concern is that as the hepatitis C virus is suppressed and the immune system recalibrates, a dormant hepatitis B infection can flare up.⁹ Reactivation can occur soon after treatment begins and, in severe cases, has led to liver failure and death.

In practice, the absolute risk appears low, especially for people with resolved (past) hepatitis B rather than active chronic infection. One study of 79 patients with chronic hepatitis C and evidence of prior hepatitis B found that reactivation occurred in about 10% of them, mostly during treatment, and was more common in men. Crucially, none of those reactivations triggered an ALT flare or a return of surface antigen, meaning the reactivations were largely detected only through sensitive viral-load testing and did not cause clinical liver injury.¹⁰ Still, anyone starting Mavyret should be tested for hepatitis B beforehand. If you have active hepatitis B or markers of past infection, your doctor will monitor liver enzymes closely during treatment and may prescribe hepatitis B antiviral prophylaxis.

Blood Sugar Changes If You Have Diabetes

Hepatitis C itself worsens insulin resistance, so when the virus is rapidly cleared by Mavyret, some patients with type 2 diabetes experience an improvement in glucose metabolism. That sounds like good news, and in the long run it is. The catch is that if your diabetes medications stay at the same dose while your blood sugar is naturally improving, you can swing into hypoglycemia, sometimes with symptoms like dizziness, sweating, or confusion.¹¹ This effect has been documented across various direct-acting antiviral regimens, not just Mavyret specifically.

Case reports have described patients whose hemoglobin A1c levels dropped substantially during and after hepatitis C treatment, reflecting genuinely better long-term blood sugar control.¹² If you are on insulin or sulfonylureas (medications that actively lower blood sugar rather than just improving how your body handles it), the hypoglycemia risk is highest. The practical takeaway is to monitor your blood glucose more frequently once you start Mavyret and work with your prescriber to adjust doses downward as needed. This is one of those rare situations where a side effect of successful treatment is feeling too good too fast.

Alcohol During Treatment

Many patients with hepatitis C understandably wonder whether they need to be completely sober during Mavyret treatment. The prescribing label does not list alcohol as a contraindication, and the clinical data suggest that moderate drinking does not block the drug from working. A study of people who inject drugs and were receiving opioid agonist therapy found that baseline alcohol consumption did not affect cure rates from hepatitis C treatment. Interestingly, participants actually tended to drink less during treatment.¹³

That said, common sense still applies. Heavy alcohol use accelerates liver damage independently of the virus, and if your liver is already strained from years of hepatitis C infection, piling on alcohol is not doing you any favors. The real risk is not a pharmacokinetic interaction between ethanol and Mavyret’s molecules but rather the additive burden on a liver that is trying to heal. Most hepatologists will encourage you to minimize alcohol during treatment, and many patients find that the commitment to clearing the virus becomes its own motivation to cut back.

Pregnancy, Breastfeeding, and Fertility Considerations

Mavyret does not currently have enough human data to support use during pregnancy. Information on how direct-acting antivirals for hepatitis C behave in pregnant women is limited to a small number of conference reports, and none of those collected data on whether the drugs cross the placenta or reach the fetus. Similarly, what we know about drug transfer into breast milk comes only from animal studies, not human research.¹⁴ This evidence gap means that, in standard practice, Mavyret is deferred until after pregnancy and breastfeeding are complete.

Research is beginning to change this picture. A clinical trial called IMPAACT 2041 has been designed to study Mavyret specifically during pregnancy, including optional sample collection at delivery to measure placental transfer and breast milk concentrations.¹⁵ Until results from trials like this one are available, the standard recommendation remains to avoid Mavyret during pregnancy. If you discover you are pregnant while on treatment, contact your prescriber immediately rather than stopping the medication on your own, so they can assess the best course of action.

An additional wrinkle for women of childbearing age is the ethinyl estradiol restriction discussed earlier. Because combined hormonal contraceptives are off-limits during Mavyret treatment, you need a reliable alternative method in place before and during the treatment course. Your prescriber should discuss progestin-only options or non-hormonal methods well before the first dose.

Herbal Supplements and St. John’s Wort

St. John’s wort deserves its own mention because it is one of the most potent enzyme inducers found outside of prescription medications. It activates many of the same drug-clearing pathways as rifampin, and for the same reasons that rifampin is contraindicated with Mavyret, St. John’s wort is too. The supplement can substantially reduce blood levels of both glecaprevir and pibrentasvir, putting you at risk of treatment failure. This is explicitly called out in Mavyret’s prescribing information.

Other herbal products are harder to assess because they vary enormously in composition and potency and are rarely studied in formal drug-interaction trials. Milk thistle, for example, is widely used among people with liver disease, and while it does not appear to cause the same dramatic induction effects as St. John’s wort, the lack of rigorous interaction data means your prescriber may advise caution. The safest approach is to bring a full list of everything you take, including over-the-counter vitamins, herbal teas, and supplements, to your pre-treatment appointment so your care team can flag anything that might interfere.

Timing and Practical Advice for Reducing Risk

Many of Mavyret’s interactions are dose-dependent or timing-dependent rather than absolute. The cyclosporine interaction, for instance, is manageable at low doses but dangerous at high ones. PPI interactions are mitigated by taking both drugs close together. Even the ethinyl estradiol restriction only lasts for the duration of treatment and can be planned around with a temporary switch in contraceptive method. The key is that your prescriber needs a complete picture of what you are taking, including drugs prescribed by other specialists who may not know you are starting hepatitis C treatment.

Pharmacists who specialize in hepatitis C treatment often use drug-interaction checkers specific to direct-acting antivirals. These tools cross-reference every medication in your profile against the known transporter and enzyme pathways that Mavyret relies on. If you fill prescriptions at multiple pharmacies or use mail-order services, consolidating your prescription records in one place before starting treatment reduces the chance of a dangerous combination slipping through. The eight-to-twelve-week treatment window is short enough that temporary adjustments to other medications are usually feasible, but those adjustments need to be coordinated before day one, not discovered a few weeks in when something goes wrong.