According to the Centers for Disease Control and Prevention, a temperature above 167 degrees Fahrenheit or 75 degrees Celsius is sufficient to kill influenza viruses. This temperature is often cited as lethal against viruses in general.
Moreover, an elevated body temperature can thwart viruses. This is the reason the human body reacts to infection by raising its own temperature. Consequently, having a fever isn't always a bad thing; it helps kill the viruses that are making the patient sick. While prescribing antibiotics is not effective for a viral infection, a variety of chemical agents work to destroy viruses on contact, including bleach, hydrogen peroxide and alcohol.