Viruses are the smallest kind of pathogenic microorganisms. The core contains nucleic acid (ribonucleic acid RNA or deoxyribonucleic acid DNA) and replication enzymes. It has a protein shell and membrane. It has no cell structure and lacks a complete enzyme system. It must rely on the host. Cells and enzymes to reproduce (replicate).

There are many ways to resist viral infection, such as directly inhibiting or killing the virus, interfering with virus adsorption, preventing virus from penetrating into cells, inhibiting virus biosynthesis, inhibiting virus release, or enhancing the host's antiviral ability. The effect of antiviral drugs is mainly achieved by affecting a certain part of the virus replication cycle.

According to the mechanism of action of antiviral drugs, current antiviral drugs can be divided into the following categories:

1. Penetration and shelling inhibitors: amantadine, rimantadine, enfuvirtide, maraviro;
2. DNA polymerase inhibitors: acyclovir, ganciclovir, valacyclovir, penciclovir, famciclovir, foscarnet sodium;
3. Reverse transcriptase inhibitor:
1) Nucleosides: lamivudine, zidovudine, stavudine, zalcitabine, emtricitabine, tenofovir, adefovir dipivoxil;
2) Non-nucleosides: efavirenz, nevirapine;
4. Protein inhibitor: Saquinavir;
5. Neuraminidase inhibitors: Oseltamivir Phosphate, Zanamivir;
6. Broad-spectrum antiviral drugs: ribavirin, interferon.