Aciclovir (ACV), also known as acyclovir, is an antiviral medication.^[3] It is primarily used for the treatment of herpes simplex virus infections, chickenpox, and shingles.^[4] Other uses include prevention of cytomegalovirus infections following transplant and severe complications of Epstein-Barr virus infection.^[4][5] It can be taken by mouth, applied as a cream, or injected.^[4]

Common side effects include nausea and diarrhea.^[4] Potentially serious side effects include kidney problems and low platelets.^[4] Greater care is recommended in those with poor liver or kidney function.^[4] It is generally considered safe for use in pregnancy with no harm having been observed.^[4][6] It appears to be safe during breastfeeding.^[7][8] Aciclovir is a nucleoside analogue that mimics guanosine.^[4] It works by decreasing the production of the virus’s DNA.^[4]

Aciclovir was patented in 1974, and approved for medical use in 1981.^[9] It is on the World Health Organization’s List of Essential Medicines, the safest and most effective medicines needed in a health system.^[10] It is available as a generic medication and is marketed under many brand names worldwide.^[1] The wholesale cost as of 2014 to 2016 was between US$0.03 and US$0.12 for a typical dose by mouth.^[11][12] The cost of a typical course of treatment in the United States is less than US$25.^[7] In 2016 it was the 195th most prescribed medication in the United States with more than 3 million prescriptions