Antiviral drugs are a type of antimicrobials, a larger group which also includes antibiotic (also called antibacterial), antifungal and antiparasitic drugs, or antiviral drugs based on monoclonal antibodies. Most antivirals do not cause much damage to the body, and can be used to treat infections. They are different from viricides, which are not medicine but deactivate or destroy virus particles inside or outside the body. Natural antivirals are made by some plants such as eucalyptus and Australian tea trees.