What are the common and serious side effects of Sofosbuvir (400 mg orally once daily for 12 weeks) used in hepatitis C therapy?

Sofosbuvir Side Effects

Sofosbuvir is generally well tolerated, with the most common side effects being fatigue and headache when combined with ribavirin, and fatigue, headache, nausea, insomnia, and anemia when combined with peginterferon and ribavirin. 1, 2

Common Side Effects (≥20% of patients)

With Sofosbuvir + Ribavirin:

• Fatigue (38% at 12 weeks, 30% at 24 weeks)
• Headache (24% at 12 weeks, 30% at 24 weeks)
• Nausea (22% at 12 weeks)
• Insomnia (15-16%)

With Sofosbuvir + Peginterferon + Ribavirin:

• Fatigue (59%)
• Headache (36%)
• Nausea (34%)
• Insomnia (25%)
• Anemia (21%) 2

With Ledipasvir/Sofosbuvir:

• Fatigue
• Headache
• Nausea
• Diarrhea
• Insomnia 1

Most adverse events are mild (Grade 1) in severity. The majority of side effects are attributable to ribavirin or peginterferon when used in combination regimens, rather than sofosbuvir itself 2.

Serious Adverse Events

Critical Drug Interaction - Amiodarone:

Co-administration of amiodarone with sofosbuvir (especially when combined with another DAA like ledipasvir, daclatasvir, or simeprevir) is CONTRAINDICATED due to risk of serious symptomatic bradycardia. 1, 2

If no alternative exists:

• Require in-patient cardiac monitoring for first 48 hours
• Continue daily heart rate self-monitoring for at least 2 weeks
• Patients should seek immediate medical attention for: near-fainting, fainting, dizziness, lightheadedness, malaise, weakness, excessive tiredness, shortness of breath, chest pain, confusion, or memory problems 2

Rare but Serious (<1%):

• Pancytopenia (particularly with concomitant peginterferon)
• Severe depression (particularly in patients with pre-existing psychiatric illness), including suicidal ideation and suicide
• Symptomatic bradycardia (with amiodarone co-administration) 2

Laboratory Abnormalities

Hematologic Changes:

• Anemia: Hemoglobin <10 g/dL in 8% (sofosbuvir + ribavirin 12 weeks) to 23% (sofosbuvir + peginterferon + ribavirin)
• Neutropenia: <0.75 × 10⁹/L in 12-15% (with peginterferon-containing regimens)
• Platelet decreases: Generally minimal 2

Biochemical Changes:

• Bilirubin elevations (>2.5×ULN): 1-3% of patients, typically peak in first 1-2 weeks, resolve by post-treatment week 4, not associated with transaminase elevations
• Creatine kinase elevations (≥10×ULN): <1-2%, isolated and asymptomatic
• Lipase elevations (>3×ULN): <1-2%, isolated and asymptomatic 2

Treatment Discontinuation

Discontinuation rates due to adverse events are very low:

• 1% with sofosbuvir + ribavirin (12 weeks)
• <1% with sofosbuvir + ribavirin (24 weeks)
• 2% with sofosbuvir + peginterferon + ribavirin (12 weeks)
• Compare to 11% with peginterferon + ribavirin alone 2

Special Populations

HIV/HCV Coinfection:

The safety profile is similar to HCV mono-infected patients. Important caveat: Elevated total bilirubin (Grade 3-4) occurred in 94% (30/32) of patients receiving atazanavir as part of antiretroviral therapy, though without concomitant transaminase increases 2

Decompensated Cirrhosis:

In patients with Child-Pugh B or C cirrhosis treated with sofosbuvir/velpatasvir + ribavirin, all Grade 3-4 adverse events, serious adverse events, and deaths were deemed unrelated to treatment. However, this population has inherently higher morbidity and mortality risk related to underlying liver disease 3.

End-Stage Renal Disease:

In patients undergoing dialysis, sofosbuvir/velpatasvir was well tolerated with headache (17%), fatigue (14%), nausea (14%), and vomiting (14%) being most common. All serious adverse events were deemed unrelated to treatment 4.

Key Clinical Pitfalls

1. Always screen for amiodarone use before initiating sofosbuvir-based therapy
2. Monitor for anemia when ribavirin is included in the regimen
3. Bilirubin elevations are expected and benign in the first 2 weeks; do not discontinue therapy unless accompanied by transaminase elevations
4. In HIV coinfection with atazanavir, expect isolated hyperbilirubinemia without clinical significance
5. Most adverse events are attributable to combination partners (ribavirin, peginterferon), not sofosbuvir itself