Valclovir-500 Tablet 10's is used to treat viral infections, including cold sores (an inflamed blister in or near the mouth), genital herpes (sexually transmitted infection marked by genital pain and sores), and herpes zoster (a viral infection that causes a painful rash). It contains valacyclovir, which stops the proliferation of viruses and treats viral infection. In some cases, this medicine may cause side effects like headache, dizziness, nausea, vomiting, diarrhoea, and sensitivity to sunlight.