Sofosbuvir

Key facts

• Sofosbuvir is a direct-acting antiviral that blocks an enzyme hepatitis C needs to copy itself. It is always combined with at least one other antiviral, in single tablets such as Sovaldi (paired with another agent) or Harvoni (with ledipasvir).
• You take it once a day, usually for 8 to 12 weeks, with the exact combination and length depending on the hepatitis C genotype and whether you have had treatment before.
• Never combine sofosbuvir with amiodarone. Together they can cause a severe, sometimes fatal slowing of the heart rate, even weeks after the amiodarone was stopped.
• Sofosbuvir can reactivate hepatitis B in people who have ever had that infection. Tell your doctor if you have a history of hepatitis B so you can be tested and monitored.

What sofosbuvir treats

Sofosbuvir-based regimens treat chronic hepatitis C infection across the major genotypes. The goal is to clear the virus to undetectable levels, which prevents ongoing liver damage and reduces the long-term risk of cirrhosis and liver cancer. Some regimens are suitable for people with compensated cirrhosis; decompensated liver disease needs specialist assessment.

How sofosbuvir works

Hepatitis C copies its genetic material using a viral enzyme called NS5B polymerase. Once inside a liver cell, sofosbuvir is converted into an active form that mimics one of the virus's natural building blocks. The virus incorporates it into the new genetic strand it is building, which stops the strand from growing further and halts replication.

Before you take it

• Tell your doctor if you have ever had hepatitis B, even in the past, since sofosbuvir-based treatment can reactivate it. You should be tested for hepatitis B before starting.
• Do not take sofosbuvir with amiodarone. If you take amiodarone, your doctor will consider an alternative heart medicine before starting treatment.
• Tell your prescriber about all other medicines, including certain anticonvulsants, tuberculosis drugs, and St John's wort, which can reduce how well sofosbuvir works.
• Tell your doctor if you are pregnant, planning pregnancy, or breastfeeding, since the risk in these situations has not been fully established.

Side effects

Common effects include fatigue, headache, nausea, and trouble sleeping.

Stop and seek urgent medical care for any of these:

• A very slow heartbeat, dizziness, fainting, or extreme tiredness, especially if you also take amiodarone.
• Yellowing of the skin or eyes, dark urine, or persistent abdominal pain, which can signal liver injury.
• Signs of an allergic reaction, including rash, facial swelling, or difficulty breathing.

Safety essentials

• Combining sofosbuvir with amiodarone can cause life-threatening bradycardia. This combination should be avoided; if there is no alternative, cardiac monitoring is required.
• Everyone starting sofosbuvir-based treatment should be tested for hepatitis B beforehand, since clearing hepatitis C can allow a dormant hepatitis B infection to reactivate.
• Complete the full course as prescribed and attend follow-up blood tests to confirm the virus has cleared.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.