If you have noticed a soft, bluish or clear bump on your child's gum, right where a tooth is about to come through, it can be a worrying sight. In most cases it is an eruption cyst, a small fluid-filled swelling that forms over a tooth as it pushes towards the surface. When the fluid inside is blood-tinged, the same thing is called an eruption haematoma, and it can look dark blue or purple. The reassuring news is that eruption cysts are almost always harmless and clear up on their own once the tooth breaks through.
This guide explains what an eruption cyst is, why it forms, why it usually needs no treatment, and the few signs that mean it is worth having checked.
Key takeaways
- An eruption cyst is a soft, bluish or clear swelling over a tooth that is coming through.
- When it contains blood it may look dark blue or purple and is called an eruption haematoma. The two are treated the same way.
- They are harmless in almost all cases and resolve on their own, usually within days to a few weeks, as the tooth erupts.
- They can appear over baby teeth, often around 6 to 12 months, and over new adult teeth, often around age 6 to 7.
- Treatment is rarely needed. The main approach is reassurance and watchful waiting.
- See a dentist if the bump becomes painful, infected, very large, or is stopping your child eating.
The one thing to remember: it almost always needs nothing
The single most useful point is that an eruption cyst almost never needs treatment. As the tooth continues to push upwards, the cyst usually bursts on its own, the fluid drains, and the tooth comes through normally. Because so many resolve quietly before anyone notices, the true frequency is unknown, and dentists tend to see only the ones that look dramatic enough to prompt a worried visit. In the vast majority of children, calm observation is all that is required.
Why an eruption cyst forms
As a tooth moves up through the jaw, it has to pass through a small sac of tissue before it breaks the surface of the gum. Sometimes fluid collects in the space between the tooth and that sac, creating a soft dome on the gum. If a tiny blood vessel is involved, the fluid is blood-tinged and the bump looks blue or purple. It is essentially a normal part of eruption that has become briefly visible, not an infection or a tumour. It appears most often over the front teeth and the first molars, and can happen with both baby teeth and adult teeth.
Eruption cyst or teething?
Teething and eruption cysts are related but not the same. Teething describes the general discomfort, dribbling and gum rubbing that comes as teeth move through, while an eruption cyst is the specific soft bump you can see over one tooth. A child can have both at once. Either way, the comfort measures are similar: a clean finger or cold teething ring to rub the gum, and plenty of reassurance. For new adult teeth, our guide to when adult teeth come in sets out the usual timing.
What you can do at home
For a typical eruption cyst, the best approach is gentle and hands-off. Keep the area clean with a soft brush or a clean damp cloth, offer something cool and safe to chew if your child is teething, and let nature take its course. Do not try to lance or squeeze the bump, as that risks introducing infection and is unnecessary. If the cyst bursts on its own you may notice a small amount of blood-tinged fluid, which is normal, after which the tooth usually appears.
When to see a dentist
While most eruption cysts are harmless, it is worth a check if the bump becomes painful, looks red and angry or has pus, grows large enough to interfere with feeding, or simply has not resolved and the tooth is not coming through. In those uncommon situations a dentist may decide to make a tiny opening to uncover the tooth, a quick procedure, or simply confirm that all is well. Anything that looks like spreading swelling or makes your child unwell should be seen promptly, as covered in our guides to dental abscess in children and gum problems in children.
Frequently asked questions
Is an eruption cyst dangerous?
In almost all cases, no. It is a harmless, self-limiting swelling that clears as the tooth erupts. Only rarely, if it becomes infected or very large, does it need any treatment.
Should I pop it?
No. Never try to lance or squeeze an eruption cyst. It usually bursts on its own as the tooth comes through, and interfering with it risks infection.
How long does an eruption cyst last?
Usually days to a few weeks. It resolves as the underlying tooth breaks through the gum. If it lingers and the tooth does not appear, have it checked.
Can adults get eruption cysts?
They are mostly seen in children over baby teeth and new adult teeth, but a similar swelling can occasionally appear over a wisdom tooth that is coming through in a teenager or young adult.
An eruption cyst looks more worrying than it is, and reassurance is usually the only treatment needed. If you are unsure about a bump on your child's gum, the team at Lumi Dental in Melrose Park is always happy to take a quick look and put your mind at ease. Read more in our first dental visit guide, and our companion piece on extra teeth in children. Current new patient information is on our offers page.
This article is general information and is not a substitute for personal dental advice for your child.
