There are few effective antiviral drugs due to the parasitic nature of viruses.  Since viruses hijack host cell machinery and sometimes can even integrate into a host genome, targeting viruses is difficult because targeting will often affect the host cell as well.  This leads to toxic side effects with dangerous consequences for patients.

Because of this, the general strategy for antivirals is to target steps in a virus life cycle that are specific only to that virus.

Commonly targeted steps due to specificity would include:

 

Classes of Antiviral Drugs

Viral Genome Synthesis Inhibitors

Viral Protein Maturation Inhibitors

Entry and Uncoating Inhibitors

Viral Spread Inhibitors