Herpes or mouth sores at the corners of the mouth are usually caused by herpes simplex virus infection, which may be caused by too much pressure from the patient’s work or study during this period of time, poor rest, or mental stress leading to a drop in resistance, causing herpes virus infection and leading to inflammation at the corners of the mouth. The fastest treatment is to use acyclovir ointment several times a day, apply it to the surface of the mouth sores or herpes, you can apply it about 5-6 times a day, each time you need to use a cotton swab dipped in acyclovir ointment, do not use your hands to apply it because there are bacteria on your hands, which may lead to further herpes infections, and also with the nutritional support because of the decline in the systemic resistance. Be sure to pay attention to diet, and to rest, herpes infection will heal on its own in about a week.