Baloxavir marboxil is primarily used as an antiviral medication for the treatment of influenza. It is effective against both influenza A and B viruses. The drug works by inhibiting the cap-dependent endonuclease activity of the viral polymerase, which is essential for viral replication. This mechanism allows it to reduce the duration of flu symptoms and decrease the viral load in patients. It is particularly beneficial for individuals at high risk of complications from influenza, such as the elderly, young children, and those with chronic health conditions. Additionally, baloxavir marboxil is used for post-exposure prophylaxis to prevent the spread of influenza in close contacts of infected individuals. Its single-dose oral administration offers convenience and improves patient compliance compared to multi-dose treatments. The medication is also being studied for its potential in treating other viral infections and in combination therapies to enhance its efficacy.