What Causes Blisters Inside the Lips?

Blisters inside the lips may arise from several possible causes:

1. Traumatic blood blister: This may occur due to accidental biting by a sharp tooth cusp or from consuming hard or excessively hot food, causing mechanical injury and subsequent blood blister formation. In such cases, the blister may be carefully incised to drain the accumulated blood and fluid, followed by topical application of wound-healing agents—e.g., Befuxin (recombinant human basic fibroblast growth factor gel).

2. Mucocele: Minor salivary glands reside within the lip mucosa; accidental biting during eating may obstruct their ducts, leading to accumulation of mucus and formation of a mucocele. Definitive treatment requires surgical excision of the cyst to achieve full recovery.

3. Herpes simplex virus (HSV) infection: Blisters caused by HSV typically appear in clusters and are commonly accompanied by pruritus and pain. Antiviral therapy is recommended—for example, Pudilan Xiaoyan Oral Liquid or Lanqin Oral Liquid.