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Dental and Oral Health (Adults)

Dark Purple Blister in Mouth



I have noticed a very dark purple, blister like bump in the inside of my mouth, on the inner part of my lip that rests against my upper teeth. I was using invisilign braces & am now just wearing the night time retainers. I showed it to my dentist and he said it looks like it may be from rubbing against my retainer, and to stop wearing it for a week to see if it goes away. Well, it hasn`t. I do notice that sometimes it feels more puffy, it kind of puffs up & then goes down, but never goes away. It has never hurt or given me any pain. Should I be concerned?


What you describe could be a varix or dilated vein. They are the equivalent of the more commonly recognized varicose veins in the leg. While they can occur anywhere in the mouth, the tongue and the lips or cheeks are among the more commonly affected sites.

This varix was likely present, yet unnoticed, in this part of your lip for some time, but may have recently developed a tiny clot (called a thrombus) that brought it to your attention as a blister-like bump you can feel and see. This condition is not serious and it may be coincidental with, rather than resulting from, your braces and retainer.

It will probably never go away completely but neither is it likely to get progressively larger. If your dentist is unsure, seek a referral to a dental specialist such as an oral and maxillofacial surgeon. Depending upon its size, the option of having it completely removed may be discussed with you.

This option would accomplish two things. First, it would give you a firm diagnosis so you could be confident that it truly is nothing serious. Second, it would get rid of this bothersome lip bump. Good luck!

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Response by:

John R Kalmar, DMD, PhD John R Kalmar, DMD, PhD
Clinical Professor of Pathology
College of Dentistry
The Ohio State University