In a placebo controlled, double-blind clinical trial in patients with herpes labialis recidivans, zinc sulfate (CAS 7733-02-0) as gel (Virudermin Gel) proved to be significantly more effective than the gel alone. With zinc sulfate as gel, the symptoms were less marked and healing was faster. This simple preparation can be applied in cases of herpes labialis recidivans without any risk of side effects. Due to the antiseptic properties of zinc sulfate superinfections can be prevented.