If you have spotted a soft, bluish or purple bump on your baby gum right where a tooth is about to come through, it is most likely an eruption cyst. It looks alarming, especially when it is dark and blood-filled (then called an eruption haematoma), but it is almost always harmless. An eruption cyst is a small fluid-filled sac that forms over the crown of a tooth as it pushes up through the gum, and in the large majority of cases it bursts and clears on its own as the tooth appears.
Key takeaways
- An eruption cyst is a soft bump over an erupting tooth, often bluish or purple if it contains a little blood.
- It is benign and usually resolves on its own as the tooth breaks through, with no treatment needed.
- It can appear with baby teeth and with adult teeth, and is also seen occasionally in newborns.
- Most cases just need watching; only a small minority that are painful or not erupting need a simple procedure to uncover the tooth.
- See a dentist if the bump is very painful, rapidly growing, infected, or the tooth is not coming through.
The one rule: watch and reassure, do not squeeze
The main thing to do with an eruption cyst is leave it alone and let nature take its course. Do not try to pop, lance or squeeze it. In studies of eruption cysts, only a small minority, around one in eight, ever needed a minor procedure, and most simply resolved with monitoring as the tooth erupted. Your job is to keep the area clean, soothe any discomfort, and watch its progress.
What an eruption cyst looks like
It appears as a dome-shaped, soft swelling on the ridge of the gum, exactly where a tooth is due. The colour can range from the same pink as the gum to translucent, blue, purple or almost black when there is blood inside (an eruption haematoma). The darker colour is what worries parents most, but it simply reflects a small amount of blood in the fluid and is not a sign of something sinister. They are most often seen on the upper jaw and can affect front teeth or molars.
Why they happen
As a tooth erupts, it has to pass through the gum tissue. Sometimes fluid collects in the small space between the crown of the tooth and the overlying gum, forming a soft, balloon-like sac. If a small blood vessel is involved, the fluid is blood-tinged and the cyst looks dark. They are more common as children get their adult teeth and start chewing harder foods, but they appear with baby teeth too, and occasionally a baby is born with one.
How to soothe your baby
- Offer a clean, chilled (not frozen) teething ring or a cold, damp washcloth to chew on. Cold and gentle pressure are the safest comfort measures.
- Keep the gum clean by wiping gently with a soft, damp cloth or a soft baby brush.
- Avoid teething gels and amber necklaces; regulators have warned about the safety of some teething products, as covered in the article on teething gels and necklaces.
- If your baby is in real discomfort, ask your pharmacist or doctor about appropriate infant pain relief for their age and weight.
When to see a dentist
Most eruption cysts need no more than a watchful eye, but book a check if the bump is very painful or your baby is not feeding, if it is rapidly growing or looks infected (red, hot, with pus), if there is a fever, or if the tooth does not come through after the cyst has been there for a while. In those uncommon cases, a dentist can perform a simple procedure to uncover the crown and let the tooth erupt. A true high fever or unwell child is not caused by teething or a cyst and should be reviewed by a doctor.
Frequently asked questions
Is an eruption cyst dangerous?
No. It is a benign, self-limiting swelling that almost always clears as the tooth erupts. The dark colour is just blood-tinged fluid, not a sign of anything serious.
Should I pop my baby eruption cyst?
No. Do not squeeze or lance it. It will usually burst on its own as the tooth comes through. Interfering risks introducing infection.
How long does an eruption cyst last?
Often days to a few weeks, until the tooth breaks through. If it has been present for a long time with no tooth appearing, have it checked.
Why is the bump blue or purple?
Because it contains a small amount of blood mixed with the cyst fluid, which is then called an eruption haematoma. It is still harmless.
Can adults get eruption cysts?
They are most common in children, but they can occur over any erupting tooth, including adult molars and wisdom teeth.
If you are unsure about a bump on your baby gum, the team at Lumi Dental in Melrose Park is happy to take a look. Related reading: teething in babies, teething gels and necklaces safety, natal and neonatal teeth, and how to clean baby and toddler teeth.
This article is general information and not a substitute for advice from your dentist, doctor or pharmacist.
