A ranula is a fluid collection, or cyst, that forms in the mouth under the tongue. It is filled with saliva (spit) that has leaked out of a damaged salivary gland.

What causes ranula?

If there's an injury to the duct carrying saliva to the mouth from the salivary gland, a blockage could occur. Saliva accumulates in the salivary gland and forms a cyst since it cannot drain properly. This creates a ranula. Similarly, if you get hit in the face or bite your cheek too hard, a ranula could form.

Is ranula serious?

Ranulas do require treatment, but they are not serious in that they are not life threatening and do not typically cause pain. A ranula, if large enough, can lift the tongue and impair chewing, eating, and swallowing.