Used primarily as an antiviral agent, particularly in the treatment of herpesvirus infections. It is effective against viruses such as herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2), and varicella-zoster virus (VZV). The compound functions as a nucleoside analog, which gets phosphorylated inside infected cells and incorporated into viral DNA, leading to chain termination and inhibition of viral replication. Due to its selective activation in virus-infected cells, it exhibits relatively low toxicity to host cells. It has been used in both topical and systemic formulations for managing mucocutaneous herpes infections and has also been explored in the treatment of certain viral encephalitis cases.