Which medication is used specifically to treat oral herpes labialis?

Docosanol is an FDA-approved topical cream that is specifically used for the treatment of oral herpes labialis, commonly known as cold sores. It works as an antiviral agent by inhibiting the fusion between the virus and the host cell membrane, which helps to prevent the herpes simplex virus from entering the cells and replicating. This can lead to a reduction in the duration and severity of outbreaks when applied at the first sign of a cold sore.

While acyclovir and valacyclovir are also antiviral medications that treat herpes simplex infections, including oral herpes, they are primarily used in systemic or mucosal formulations for more extensive infections or for prophylaxis. Zidovudine is an antiretroviral medication used mainly in the treatment of HIV/AIDS, not for oral herpes. Therefore, docosanol is the most specific choice for treating cold sores due to its targeted use and mechanism of action directly linked to oral herpes labialis.