Mavyret Side Effects: What to Expect and When to Call Your Doctor

Mavyret (glecaprevir/pibrentasvir) is one of the best-tolerated hepatitis C treatments available. In clinical trials, most adverse events were mild to moderate in severity, and the discontinuation rate due to side effects was low. Still, like any medication, Mavyret can cause side effects—and some are more serious and require prompt medical attention.

Common Side Effects of Mavyret

The most frequently reported side effects in Mavyret clinical trials were:

Headache — The most commonly reported side effect. Usually mild and manageable with over-the-counter pain relievers like acetaminophen (check with your doctor before taking any new medication).

Fatigue/asthenia — Tiredness and weakness are common, particularly in the first few weeks. Most patients find this improves as treatment continues.

Nausea — Mild nausea occurs in some patients. Taking Mavyret with food (as required) helps reduce this. Try taking it with a full meal if nausea is bothersome.

Diarrhea — Reported in some patients, typically mild. Stay well hydrated.

Itching (pruritus) — Some patients experience skin itching. This is generally mild. If severe or accompanied by rash, contact your doctor.

Serious Side Effects: When to Call Your Doctor Immediately

While rare, Mavyret can cause serious adverse effects. Contact your doctor immediately or go to the emergency room if you experience:

Signs of hepatitis B reactivation: Yellow skin or eyes (jaundice), dark urine, extreme fatigue, nausea, vomiting, or stomach pain. Mavyret carries a BOXED WARNING for hepatitis B reactivation, which can cause liver failure and death in patients with HBV co-infection.

Signs of liver decompensation: Jaundice, confusion or altered mental status, significant swelling in the abdomen (ascites), or vomiting blood. Though rare, post-marketing cases of hepatic decompensation/failure have been reported with Mavyret.

Severe allergic reaction: Rash, hives, difficulty breathing, swelling of the face, lips, tongue, or throat. Seek emergency care immediately.

Severe nausea or vomiting preventing you from taking doses: Missing doses can reduce treatment effectiveness. Contact your doctor if side effects are making it difficult to complete your course.

The Boxed Warning: HBV Reactivation

Mavyret's most serious risk is hepatitis B virus (HBV) reactivation. This is the most serious warning in the prescribing information (called a "boxed warning"). If you have ever had hepatitis B—even if it seems resolved—HBV can reactivate when you take Mavyret.

This is why your doctor must test you for HBV (HBsAg and anti-HBc) before starting Mavyret. If you test positive for HBV markers, your doctor will monitor you closely and may start you on anti-HBV treatment at the same time. Do NOT stop Mavyret without medical advice—even if you feel unwell—as stopping mid-course increases the risk of treatment failure.

Blood Sugar Changes in Diabetic Patients

An important post-marketing finding: as HCV is cleared by Mavyret, liver function can improve significantly. In diabetic patients, this change in liver function can lead to hypoglycemia (low blood sugar) if diabetes medications aren't adjusted. If you have diabetes and take insulin or other glucose-lowering drugs, notify your doctor as soon as you start Mavyret so blood sugar can be monitored closely.

Is It Normal to Feel Worse Before Feeling Better?

Some patients notice mild side effects (headache, fatigue) in the first 1–2 weeks that then ease. This is common and not a sign that Mavyret isn't working. Most patients who complete the 8-week course are cured—with viral RNA becoming undetectable (SVR12) 12 weeks after completing treatment.

For a full picture of Mavyret safety, also review Mavyret drug interactions: what to avoid and our overview of what Mavyret is and how it's taken.