Aciclovir

Aciclovir, drug used to treat the symptoms of diseases caused by the herpes viruses. These include chickenpox and shingles (herpes zoster), and genital herpes and cold sores (herpes simplex). Although aciclovir and a similar antiviral, valaciclovir, do not eradicate the viruses, their action disrupts viral DNA and replication processes. When given as soon as possible after symptoms appear, they reduce their severity. Aciclovir can be life-saving for patients whose immune system is impaired, such as people with AIDS, for whom it may also serve as both prophylaxis and prevention against recurrence. It is given orally for shingles and severe cases of chickenpox (particularly in adults who have never had the disease), and externally as cream preparations for herpes simplex infections.