Blister inside bottom lip

A blister on the inner lower lip is often a fluid-filled irritation or mucus cyst, but its appearance and duration determine the next step.

The inner lower lip contains minor salivary glands that can form a mucus cyst after a small duct is injured. Biting, sharp teeth, braces, hot food, and viral sores can also produce a tender or raised lesion.

Avoid biting or popping the area, and use a soft toothbrush while it heals. Choose cool, soft foods and avoid irritating spices or very hot drinks; a dentist can remove a persistent mucus cyst or treat a sharp source of trauma.

Book an examination if the lesion lasts beyond two weeks, repeatedly returns, becomes firm, or bleeds without clear injury. Seek prompt care for spreading swelling, fever, difficulty swallowing, or difficulty breathing.

Ask whether the appearance fits a mucus cyst, traumatic ulcer, cold sore, or another lesion. Ask whether a sharp tooth, appliance, or salivary duct needs treatment and whether removal or sampling is indicated.