Viral infections like herpetic stomatitis can cause mouth ulcers, blisters, swollen gums, and other symptoms. Herpetic stomatitis is a viral infection caused by the herpes simplex virus (HSV).

It's estimated that 20% of the population experiences this type of recurrent stomatitis. These fluid-filled blisters appear on the lips as a symptom of an oral herpes infection. Unlike canker ...