Famciclovir is an antiviral medication used to treat herpes virus infections, including shingles, cold sores, and genital herpes [1]. However, there is limited information on the use of famciclovir for other viruses. The drug patent watch website indicates that famciclovir is only approved for the treatment of herpes virus infections [1]. The Mayo Clinic website also mentions that acyclovir, a similar medication to famciclovir, is only used to treat herpes virus infections and not other viruses [2]. A study published in the National Center for Biotechnology Information (NCBI) suggests that famciclovir may have some activity against hepatitis B virus, but further studies are needed to confirm this [3]. Overall, while there may be some potential for famciclovir to be used for other viruses, it is currently only approved for the treatment of herpes virus infections. More research is needed to determine its effectiveness against other viruses.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/FAMCICLOVIR
[2] https://www.mayoclinic.org/drugs-supplements/acyclovir-oral-route-intravenous-route/precautions/drg-20068393?p=1
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3184032/