What the label lists and what reports show
Elbasvir and grazoprevir side effects
Elbasvir and grazoprevir's FDA label: “In subjects receiving ZEPATIER for 12 weeks, the most commonly reported adverse reactions of all intensity (greater than or equal to 5% in placebo-controlled trials) were fatigue, headache, and nausea.” FAERS holds 4,243 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is fatigue (957 reports).
- No generic listed
- A presentation discontinued
- Boxed warning
Check it at the source: the elbasvir and grazoprevir FDA label on DailyMed (effective March 13, 2026, Merck Sharp & Dohme LLC); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of ZEPATIER?ZEPATIER can cause serious side effects, including: Hepatitis B virus reactivation. See " What is the most important information I should know about ZEPATIER? " Signs of liver problems. ZEPATIER may cause increases in your liver-related blood tests. This could be a sign of serious liver problems. Your healthcare provider will do blood tests to check your liver before and during treatment with ZEPATIER. […]
Source: FDA drug label, Merck Sharp & Dohme LLC, effective March 13, 2026 (SPL set 164dc02a-9180-426a-b8b5-04ab39d2bbd4), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsIn subjects receiving ZEPATIER for 12 weeks, the most commonly reported adverse reactions of all intensity (greater than or equal to 5% in placebo-controlled trials) were fatigue, headache, and nausea.
Table 4: Adverse Reactions (Moderate or Severe Intensity) Reported in ≥2% of PegIFN/RBV-Experienced Subjects with HCV Treated with ZEPATIER for 12 Weeks or ZEPATIER + Ribavirin for 16 Weeks in C-EDGE TE
| Reaction | ZEPATIER N=105 % 12 weeks | ZEPATIER + Ribavirin N=106 % 16 weeks |
|---|---|---|
| Anemia | 0% | 8% |
| Headache | 0% | 6% |
| Fatigue | 5% | 4% |
| Dyspnea | 0% | 4% |
| Rash or Pruritus | 0% | 4% |
| Irritability | 1% | 3% |
| Abdominal pain | 2% | 2% |
| Depression | 1% | 2% |
| Arthralgia | 0% | 2% |
| Diarrhea | 2% | 0% |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following adverse reaction is described below and elsewhere in the labeling: Increased Risk of ALT Elevations [see Warnings and Precautions (5.2) ]. In subjects receiving ZEPATIER for 12 weeks, the most commonly reported adverse reactions of all intensity (greater than or equal to 5% in placebo-controlled trials) were fatigue, headache, and nausea. In subjects receiving ZEPATIER with ribavirin for 16 weeks, the most commonly reported adverse reactions of moderate or severe intensity (greater than or equal to 5%) were anemia and headache. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Merck Sharp & Dohme LLC at 1-877-888-4231 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. If ZEPATIER is administered with ribavirin, refer to the prescribing information for ribavirin for a description of ribavirin-associated adverse reactions. …
Source: FDA drug label, Merck Sharp & Dohme LLC, effective March 13, 2026 (SPL set 164dc02a-9180-426a-b8b5-04ab39d2bbd4), via openFDA; the full label on DailyMed
What do FAERS reports show?
4,243 reports list elbasvir and grazoprevir among the medicines taken, each a report of something that happened, not proof the medicine caused it; 123 are coded as a death and 574 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Reports rose sharply in 2017 (2,382, against a median of 69 a year): FAERS counts follow reporting, which news, litigation and label changes can drive, not how often a reaction happens. Of the 23 reactions below, 10 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Elbasvir and grazoprevir: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions