Antiviral drugs are specifically used to treat viral infections, instead of bacteria. Most antivirals are used for certain viral infections, while a wide range of antiviruses are effective against a wide range of viruses. Viruses are the tinier germs that can cause several infectious diseases such as flu, common cold, and warts. Viruses can also cause severe illnesses, including smallpox, HIV/AIDS, and Ebola. Viruses reproduce inside cells and able to enter into any living, healthy cells and multiply and produce other viruses like themselves. Different viruses attack specific cells in the body such as liver, brain, skin, blood and also reproductive, respiratory, and gastrointestinal systems.