There are substantial difficulties involved in carrying out clinical studies of recurrent herpes labialis, since the disease has a rapid onset, short-lasting viral shedding period and is rapidly self-healing. The aim of this paper was to critically assess published reports of episodic treatment of herpes labialis and to review biological and methodological problems involved in such studies. Limited, but statistically significant, results have been shown with topical antivirals, such as acyclovir and penciclovir, improving healing times by approximately 10%. Orally administrated antivirals, such as valaciclovir and famciclovir, have subsequently found clinical use. However, these two oral medications have different profiles in phase 3 studies. Famciclovir showed additional improvement of efficacy in terms of lesion healing time, but no effect on prevention of ulcerative lesions, while valaciclovir appeared to have similar efficacy to that of acyclovir cream on lesion healing, but some additional efficacy with respect to prevention of ulcerative lesions. A formulation of acyclovir/hydrocortisone showed further improvement in prevention of ulcerative lesions, while retaining efficacy with respect to lesion healing.