If a mouth sore is caused by a viral infection, the following treatments can be taken: First, apply acyclovir ointment locally and use some chlorhexidine mouthwash for antibacterial treatment. Secondly, systemic antiviral therapy can be carried out by taking oral acyclovir tablets or intravenous virazole. Third, systemic supportive therapy, with more vitamin B and vitamin C-rich vegetables and fruits, will help the mouth sores heal. Mouth sores are generally self-limiting and will heal completely on their own in about 7-15 days. What we need to do is to try to relieve the patient’s condition and alleviate the pain during the onset of the disease.