Bubble on inside of mouth

A mouth bubble may be a fluid-filled mucocele, irritation blister, ulcer, or another lump that needs examination if persistent.

A mucocele often forms when a minor salivary gland duct is injured, commonly on the inner lower lip. A clear or blood-tinged swelling can also follow biting, a sharp tooth, heat, or friction, but appearance alone cannot establish the diagnosis.

Do not puncture, squeeze, or burn the swelling. Check for a biting habit or sharp edge, choose softer foods temporarily, and keep brushing gently while observing its size, color, texture, and duration.

Arrange an examination for a lump that persists, returns, enlarges, hardens, ulcerates, or bleeds without a clear injury. Seek urgent help for rapidly increasing swelling or difficulty swallowing or breathing.

Ask whether the lesion fits a mucocele, traumatic injury, ulcer, or another condition and whether a biopsy or minor procedure is indicated. Ask how recurrence would be prevented if a salivary duct is involved.