Sofosbuvir is an antiviral medication used to treat chronic hepatitis C, a viral infection that affects the liver. It works by inhibiting a specific enzyme that the virus needs to replicate, helping to reduce the amount of virus in the body. Sofosbuvir is often used in combination with other antiviral drugs to improve treatment effectiveness. This medication is taken orally, usually once a day, and is well-tolerated by most patients. Common side effects may include fatigue, headache, and nausea. Sofosbuvir has significantly improved the cure rates for hepatitis C, making it a key advancement in the field of infectious diseases.