Antibiotics do nothing against viruses. That job falls to antivirals, a smaller and trickier class of drugs. Viruses are not quite alive. They hijack host cells to replicate, which means any drug that stops them risks harming the cell they live in. Effective antivirals thread that needle by targeting viral proteins that human cells do not have.

Herpes and HIV were among the first targets. Acyclovir, introduced in the 1980s, blocks viral DNA polymerase and shortens herpes outbreaks. HIV treatment evolved from single drugs to combinations that hit the virus at multiple points, turning a fatal infection into a manageable chronic condition. Influenza antivirals like oseltamivir work best when started within 48 hours of symptoms. Hepatitis C drugs, direct-acting antivirals, can cure the infection in most patients over 8 to 12 weeks.

What sets antivirals apart:

• Timing. Most work best when started early, before the virus has spread widely.
• Resistance. Viruses mutate fast, so drug combinations are common.
• Not a cure for everything. Many viral infections, including the common cold, have no specific antiviral.
• Vaccines remain first-line prevention. Antivirals treat; vaccines prevent.

Remdesivir, used in COVID-19, showed modest benefit in hospitalized patients. The search for broader antivirals continues.