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HomeOral Health & HygieneEruption Cyst: A Purple Blue Bump on Your Baby's Gums

Eruption Cyst: A Purple Blue Bump on Your Baby’s Gums

Many parents worry when they find that their young child or baby has a bluish purple bump on their gums.  This is a fairly common development and is known as an eruption cyst or eruption hematoma.  For uniformity throughout the article, I will simply refer to them as eruption cysts.

What Are Eruption Cysts?

Eruption Cyst Upper Baby MolarThe easiest way to describe eruption cysts is by talking about how teeth develop.  Your child’s teeth form inside of a protective enclosure in their jaw bone.   When the teeth are done forming, they start to move through the bone, and then through the gums until they make it into the mouth.  An eruption cyst occurs during the tooth’s final entry into the mouth – after it has already made its way through the bone and is just under the surface of the gums.

The protective enclosure which the tooth developed in can leak and allow fluid to accumulate between the tooth and the gums.  If an opposing tooth touches the gums, it may cause fluid and possibly blood to accumulate between the tooth and the gum.  This causes a bruise to form in the gum tissue between the tooth and the outside surface of your child’s gums.  Depending on the amount of blood that accumulates in the eruption cyst, it can be a translucent color, bluish purple, or even dark red and brown.

Although they are unattractive and often cause parents to worry, most eruption cysts are actually painless.

What Causes Eruption Cysts?

Eruption CystThe most widely-accepted theory is that eruption cysts are caused by trauma to the gums a few weeks before a new tooth comes in.  The trauma doesn’t have to be severe — McDonald & Avery’s Pediatric Dentistry states that the trauma occurs as a result of normal chewing.

Another reason eruption cysts occur is due to thickened gum tissues.  This can result from taking certain medications.  Neville’s Oral Pathology textbook hypothesized that one reason eruption cysts occurred in a young child taking cyclosporin was due to “collagen deposition in the gingival connective tissue that resulted in a thicker, less penetrable, pericoronal roof.”  With thicker gums, it may have been more difficult for the tooth to erupt into the mouth, causing an eruption cyst.

Who Can Get Eruption Cysts?

Any child can get an eruption cyst before their tooth erupts into the mouth.  As far as race goes, they are reported to be most common in Caucasian children and they are just as common in boys as in girls.

How Common Are Eruption Cysts?

Nobody knows.  A scholarly article has state, “Prevalence of eruption cyst has not been thoroughly studied.  Extensive review of literature revealed low prevalence of these cysts.”

Many parents may not notice that their child has an eruption cyst or may simply do nothing about it and then note that it goes away.  Due to the fact that many eruption cysts are not documented very well, it’s hard to pinpoint an exact percentage when it comes to how common eruption cysts are.

In an exam of 1,211 children from a Brazilian hospital, it was found that 2 of them had eruption cysts.  That’s only 0.17% that had eruption cysts at the time that they were examined.  However, many more of these children may have had eruption cysts before they were examined.  This would lead me to believe that eruption cysts are much more common than 0.17%.

Where Do Eruption Cysts Occur?

Although it has been debated, most articles (like this one) state that eruption cysts occur most commonly in the upper jaw.  They most commonly occur with the baby incisors, the baby molars, and the permanent first molars.

How Are Eruption Cysts Treated?

Normally eruption cysts don’t need treatment.  The tooth will usually break through the cyst within a few days come into the mouth on its own.  If the eruption cyst persists in the mouth for more than a few weeks, many dentists will make a small incision in the cyst which will allow the tooth to come through.  Depending on the anxiety level of your child, this procedure can usually be done under local anesthesia.

What Else Could It Be?

When we see a swelling over a tooth that is about to erupt, we usually think of eruption cysts.  It is possible that it could be something else though, such as a calcifying odontogenic cystThis case report states, “Other lesions that can cause gingival swellings include peripheral giant cell granuloma, peripheral ossifying fibroma, pyogenic granuloma, and other less common peripheral odontogenic tumors.”


Do you have any questions, comments, or concerns about eruption cysts?  Feel free to leave a comment in the comments section below.

I want to especially thank Leigh for sharing the above photo of her 8 month old daughter’s eruption cyst.  If anyone else wants to share their photo, you can email them to OralAnswers at or use this contact form.  Thanks for reading!

Photo Credits All photos provided by Oral Answers Readers

Update 1/7/2012: I just wrote a follow-up post to this one that has two high-quality pictures of eruption cysts above permanent teeth that haven’t yet come in.  Click here to check it out.



  1. Recently I found a cyst that sounds and looks similar to the on listed above. My son is 18 months and should be growing his baby molars (his twin sister’s came in a month ago). Are the molars also found in toddlers or are they only found in babies( under1 year)?

    • Hi Sondra – The baby first molars usually come in while the child is 1 year old, and the baby second molars usually come in while the child is 2 years old. I hope that helps, let me know if you have any other questions. Thanks for your comment!

      • Hi good day. My 13 month old son on his lower molar i saw a dark blue cyst sticking out his gum just this morning im worried is his teeth will erupt normal after seing this? Thanks

  2. My LO is 11 months,He got a trauma on his upper jaw with little bleeding.The area is bruised,and it looks exactly as the posted photo in this article.
    His tooth is not erupted yet but it was somehow swelled before the trauma and ready for eruption(i think)

    Do i need to contact a dentist?

  3. My 13 Month old has all 4 baby molars coming in right now. Three of them have broken through, but the last one appears to have this cyst on it. However, it is a “flap” of a blue/gray color with a little blood in it. Is this normal?
    He also on amoxicillin right now as he has an ear infection and cold right now as well- could that be related?
    Thank you.

    • I know this was ages ago for you now, but I’m finding your post interesting because my 14 month old bub is also on Amoxicillin and I’ve just noticed an eruption cyst around his upper left 2 nd bicuspid. I wonder how many other people are experiencing this. It may just be a coincidence, but who knows?

      • My Little girl has just turned one and her first molars are coming in now, but she has the same cysts – called Eruption Hematoma Cyst – this has been going on for 3 weeks and yesterday she has started getting fever and is not well at all. Does anybody know what ells I must do and how long I must still wait?

      • My 10mth old son is waiting on his front top tooth to come through and this will be his 5th tooth to cut through. It is the first where the gum has gone blue/black and he too was on amoxicillin last week.

    • My 10 month old is also finishing a course of Amoxicilin and developed a cyst on his gum. It does not appear to be bothering him. Im pretty sure its too early for a tooth to be coming in where it is on the gum though. Hoping it goes away.

  4. i’m a dental therapist , i have received a baby of 1 and half mouth bilateral eruption cysts in canines region with a purple color, fluctuate and it is present the time of birth not growing.

  5. Just wondering if its common to have a six year old with 2 of these purple/black spots over his top molar teeth, it has been there for a couple of months now. It does not bother him at all, he has not lost any teeth yet and is almost 7. i know he is different to his sister as at this age she had already lost 4 teeth and grown most of hers. But he has not lost any and seems to be having trouble getting these 2 to come, Is it advisable to give him something to chew on, just like a baby would to break the skin ??? need your advise as he does not like going to the dentist either.

  6. My 14mo has a top right molar coming in and the swelling/color is pretty alarming (to me). He’s had it for 1.5 weeks and although it does not bother him (he’s eating fine and I’ll have him bite down on my finger with it), I wonder when we should give up hoping it’ll resolve on its own. Some websites say a few days and some say a few weeks. The swelling has gone down a bit the past two days (no anti-inflammatory given) and I wonder if that’s a sign the tooth is finally coming through? Thank you Dr Tom!

  7. My 18 month old has a blister type thingy in his mouth where his front tooth should be. when he was a baby he had a purplish dot (very small) on the top of his lower gum. His Dr thought this was from his sucking. Now 18 months later his front teeth have come in except for the one where this blister thing is. I have taken him to a dentist but he does not know what it is.I am afraid this is going to affect his tooth growth, (although his dr says it will not). It is very noticable, and as he gets older it gets bigger. I want to get a second opinion but i dont know where to get it from.

    Very confused

  8. Thank you for the very informative article it has been very useful. My daughter has one of these cysts where her first molar is coming out in the top gums. However I am concerned as the tooth looks like it might be coming out of the side of the top left gums. Is this combination common? Will it self correct or should I have it seen to?

  9. My 4 month old son has one of these according to our dentist. However, it’s been there since birth. Is that normal?

  10. Hi there. My 6 year old son has about 2 teerh that are a little loose in the bottom portion of his mouth, the ones that are loose are his corner teeth the ones he calls vampire teeth. But those 2 are loose, but on the bottom of those teeth he has a small blister that is surrounded by purple. Which looks like to me a bruised blister and it just now start it to bleed. He has it only one tooth and on the other one he doesn’t. Please help because I am worried and so is he. It doesn’t look like to me like when a tooth is ready to come out, yet again I don’t know.

  11. If a child has what looks like an erosion cyst and then it goes away but the tooth never comes through and then a few weeks later has again what looks like an erosion cyst in the same spot and still no tooth coming in is it of concern or should we just wait it out?

  12. Hi! My baby is only 5 1/2 months and he has this on his upper jaw in the same spot. Does this seem a little early? He does not yet have any other teeth. I thought the bottom two teeth came first?

  13. Hi! My baby is 10 months old and he has a purple mass protruding in upper jaw next to his first incisive. I’m thinking its probably an eruption cyst, but I’ve read that it should go away in a matter of day and he has had this for 3-4 weeks. We took him to the dentist and we where told to start brushing his teeth and that eventually the teeth under it will come out… But I’m still worried because there’s no sign of the tooth coming out. What should I do? Thanks!

    • Angie same with my daughter she is 4 months and has no teeth but had to neonatal teeth removed on bottom jaw and now has a little growth that turns purple of Twisted the wrong way and the place where the neonatal teeth were removed

  14. My girl is 5.complained of front gum pain but I told her she is changing her milk teeth then I noticed that d whole front of her gum has changed color and a little swelling in between one of her teeth.what could it be pls

  15. My 16 month old has this i nust discovered it last night i was scared an didnt know what it was but thankfully we have phns with internet lol so how long does this actually last and will it hurt him when the tooth comes through, i never seen this on my oldest i hve so many more questions.

  16. Hi my 1 year old has little white sires on his gums where his teeth are breaking through at, not sure if they’re canker sores or what please help

  17. HI! My 15 mos old is getting is bottom first molars in and one has recently broke the surface, however, he has what looks like tissue on some parts of it? Cant really tell because i have to check when he is sleeping but it appears to be a slight yellowish whitish color? Is this just normal tissue that moved when tooth came through?

  18. My 8 1/2 years old daughter has a bluish-purple bump, far at the end on the upper jaw. So my question is: if the bluish-purple bump (Eruption Cyst) turns out a dark colour… like black, would that mean that its more dangerous than a normal Eruption Cyst or anything like that? And how many estimated day or weeks would that stay?

  19. My baby is 1 yr old and has her upper right side of her molar swollen dark brown wit a slight fever , my question is do I need to see a dentist ?

  20. Hi, my 9 and half month son have his upper center tooth about a week ago. But recently I’ve found out that his upper gum around that tooth is swollen purple. He has had fevers on and off. Is it something I should worry? Should I take him to see a dentist?

  21. My 3year old daughter has serious teeth issues. Her dentist is taking too long to see her I need help mow! Please! Her top teeth are very rotted. Now, her whole top gum is bruised! What do I do? What can happen and what is this? Is it life threatening? I am so scared. Please help.

  22. My 3year old daughter has serious teeth issues. Her dentist is taking too long to see her I need help mow! Please! Her top teeth are very rotted. Now, her whole top gum is bruised! What do I do? What can happen and what is this? Is it life threatening? I am so scared. Please help.

  23. Hi they can’t anyone please help me I am a frust time mum and my 7 month old daughter on her uper gums is like a brown ish culoer please can some one get back to me I am worring about wot it is or cude it be because she is on antibiotics for her chest infection and she got a cold to ????????

  24. My son is 15 months old and has exactly what the picture shows. I got concerned and showed it to a dentist. He a said that it was a result of a trauma. They took an x ray and said that molars come only in the second year. I’m worried now cuz they wanna get it operated. Can i just wait till the tooth pops? If the tooth is not coming soon then why is it swollen and blue? Could it be something else? Please help

  25. My son is 9 months today I open his mouth and I saw this cyst he already has about 6 teeth I don’t know what’s going on

  26. I have an 8 mouth old that the doctor said he has one on his upper left incisor. My only question is your stated it doesn’t hurt. I have noticed if I try to touch my sons he screams bloody murder and trys his hardest to get away. I don’t know if that is exactly what he has.

  27. I noticed that my 1year 2days old son has an outgrowth on his toothless lower gum closest to the second incisor. It had the same color as that of a normal gum.

    By evening, I noticed that the color had changed to a dark color (maybe dark-blue, black, dark-grey,… I couldn’t ascertain ). By night, I noticed something different. So because he was crying and a good struggler, I can’t say for a fact what I saw but (what I saw; the stem of the outgrowth seem to have collapsed, saw something white. I was sceptical to tough for fear of “further” contamination.

    Please what could that be and how can I resolve it. Please i do await your soonest positive reply or from any other experienced parent.

  28. My daughter is going to be 7 years old in a week. She has this purple look to her upper gum on her front tooth. And it concerned me until I read this. But these notes refer to younger children. Is this something I should’ve worried about since she is older? Hers has been there for anout 4 weeks.

  29. Hello… My 13 month old has witch I believe a cyst cause at first it was purple then white fluid around the teeth on top gum , She cries a lot sometimes she doesn’t want to eat at all it seems the tooth is coming out slowly cause it’s there at first I wasn’t able to feel her tooth at all but now I see it should I be concerned due to the fact that she’s gotten fever and cries alot.

  30. Hi my son has an eruption cyst where he lost his last front tooth. Dentist says not infection but an eruption cyst. Today I noticed it has gotten bigger is this normal? He lost his tooth February 7th and I noticed the cyst about a week ago, how long does it usually take before it goes away?

    Looks like you have active comments for years not replied to ! I was just going to comment and ask and question myself. Where is your moderator. I’m sure the author is running his practice therefore unable to answer all these question but you gave concerned parents here ?

  32. My Son is 21mths of age. His teeth have come in no “Normal” order and are large compared to his sisters. He has Upper front 4, one gap and a molar on each side. His bottom front two, two spaces and lower right molar with an eruption cyst. Teething for a long time – 3 to 4 mths for each tooth with significant discomfit/Pain. No jells work to easy pain. Now not eating much, and he loves his food. Starting to trip over a lot, normally he is my happy fun child but for over 3ths off and on he is emotional for days at a time, attached to me all day, cries and touches mouth falls to the ground and unable to comfit him. He clearly is in pain and everyone around him can see something is wrong and are quite concerned. The eruption cyst just changed colour 4 days ago but was gum colour during these times. A larger area of the gum was swollen, looking like 3 teeth where coming at once. Now the blue has set the swollen area is much less.
    I was advised to use SM 33 as is a lot better pain wise them other types when he started teething at 10mths of age (tooth came just after 1st birthday). And I used this on my daughter from the age of 6mths and here teething was much smoother. However last week when visiting another chemist, I was told not to use this product as it may be the cause of the thicker gums, and why he teethes for so long. And that this product should not be used till 1 year of age at the earliest. His upper molar above the cyst came in a good 2mths ago and could be the trauma you have spoken about as his teeth are quite big.
    Are there any products I could use to treatment his gums to prevent any further Cyst. And safe applying medications/Jell to apply area of gum.
    Our GP has only advised it’s a part of teething and I should work through it with him with ice or ice blocks. Ice has helped at times. Medication given – Panadol as asthma runs in the family.

  33. Thanks for the post, very useful! My daughter is 5 1/2 and has the symptoms described above – an eruption cyst in the place of a permanent molars (she hasn’t lost any teeth yet). However, the white that is showing through the lump doesn’t appear to be hard to the touch like an emerging tooth would be, and she has a bit of a temperature. Is this still within the normal range of symptoms?

  34. Hi ..2 days ago I saw the blueish slightly swallon looking gum in my son’s mouth …then today I saw a dark blueish looking somewhat of a piece of skin still attach to his gum but just sitting on top .first I though it was a rotten teeth then I touch it a it’s just I take him to a dentist or do I monitor it for 2 more days …I am panicking inside truly I am

  35. My baby boy is 11 months old..he recently fell and his lower teeth hit his upper gums and started bleeding(his upper front teeth are yet to come) it’s been a couple of days since he got hurt. Now I find a tiny lump in his upper jaw… above the gums. I am so worried… confused if it could be infection or eruption cyst…plz clarify.

  36. My baby boy is 11 months old. He recently fell and his lower teeth hit his upper jaw (his upper front teeth are yet to come)’s been a couple of days and now I find a tiny lump above his upper jaw. So confused if it could be an infection or eruption cyst. Kindly clarify.

  37. Hello thank you for helping I am a doctor and didn’t hear about eruption cyst until I accidentally found it in my toddler after noticing her cheek swelling so I started looking for the cause…
    So that explains that slight cheek swelling. Thank you so much


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