Acyclovir (400mg) is an antiviral medication that is commonly prescribed for the following uses: Herpes Simplex Virus Infections: Acyclovir is frequently used to treat infections caused by the herpes simplex virus (HSV), including genital herpes (herpes simplex virus type 2) and oral herpes (herpes simplex virus type 1). It helps reduce the severity of outbreaks, relieve symptoms, and speed up the healing process. Varicella-Zoster Virus Infections: Acyclovir is also used to treat infections caused by the varicella-zoster virus, such as chickenpox (varicella) and shingles (herpes zoster). It can help alleviate symptoms, reduce the duration of the illness, and prevent complications. Herpes Simplex Virus Prophylaxis: Acyclovir may be prescribed as a preventive measure (prophylaxis) to reduce the frequency and severity of herpes outbreaks in individuals with recurrent infections or those with compromised immune systems. Other Viral Infections: In some cases, Acyclovir might be used off-label to treat other viral infections, as determined by a healthcare professional. It's important to use Acyclovir as directed by a healthcare provider, as the dosage and duration of treatment can vary based on the specific condition being treated. Additionally, Acyclovir is most effective when started early in the course of an outbreak. Always consult a doctor before using any medication, and be aware of potential side effects and interactions with other drugs.