Blisters at the corners of the mouth may be caused by a viral infection, mainly due to infection with the herpes simplex virus when the body’s immune function is low, so topical antiviral treatment can be given by applying acyclovir ointment to the area of blisters at the corners of the mouth. You can also take antiviral medications such as oral antiviral solution, Banlangen granules, acyclovir, ganciclovir and famciclovir. If the blisters break out at the blistering site, causing redness, swelling and erosion, indicating a secondary bacterial infection, it is necessary to apply erythromycin ointment locally to the corners of the mouth for local anti-inflammatory purposes. If you have blisters on the corners of your mouth, you should take light, easy-to-digest food as your diet, drink more water, and eat more vegetables and fruits to replenish vitamin C. In addition, you should pay attention to rest, ensure sufficient sleep, and enhance the immune ability of the body to shorten the course of the disease.