What Is an Eruption Cyst on a Child's Gum?

An eruption cyst is a fluid-filled swelling in the gum over a tooth that is about to emerge. It can look clear, bluish, purple, or dark red if a little blood is present. Most are harmless and open on their own as the tooth erupts, but a dentist should confirm the diagnosis.

What an eruption cyst looks and feels like

The swelling usually sits directly over an erupting baby or permanent tooth. It may feel soft, smooth, or slightly springy and can change color depending on whether the fluid contains blood. A blood-filled version is sometimes called an eruption hematoma. Your child may have no discomfort, or the area may feel tender when chewing or brushing. Because several other gum conditions can also produce a bump, appearance alone is not enough for a definite diagnosis.

Why it forms

As a tooth moves through the jaw and toward the mouth, fluid can collect between the crown of the tooth and the tissue covering it. The result is a superficial cyst in the gum. It is related to eruption rather than decay. The swelling often becomes noticeable shortly before the tooth breaks through. Unlike many deeper jaw cysts, an eruption cyst is visible in the soft tissue and commonly resolves when the tooth opens the overlying tissue naturally.

How a pediatric dentist evaluates it

The dentist reviews when the bump appeared, whether it is changing, and whether there is pain, fever, drainage, trauma, or a nearby damaged tooth. The mouth is examined to see whether the location matches an expected erupting tooth. Imaging is considered only when the diagnosis is uncertain, eruption seems delayed, or the clinician needs to see the tooth's position. The main task is separating a typical eruption cyst from infection, trauma, another cyst, or a soft-tissue growth.

Treatment and home care

Most eruption cysts need observation rather than treatment. Continue gentle brushing around the area and offer foods that do not repeatedly traumatize a tender swelling. Do not puncture, squeeze, or cut it at home; that can introduce bacteria and create bleeding. If the cyst persists, is painful, repeatedly bleeds, or blocks eruption, the dentist may discuss opening the tissue or another targeted treatment. The recommendation depends on your child's comfort, tooth position, and how the area changes over time.

When to contact the dental team sooner

Contact the dental office promptly for increasing pain, pus, bad taste, fever, facial swelling, rapid growth, uncontrolled bleeding, or a bump that does not match an erupting tooth. Difficulty swallowing or breathing, spreading facial swelling, or a child who appears seriously ill requires urgent medical care.

Questions parents often ask

Is an eruption cyst dangerous?

A typical eruption cyst is benign and often resolves as the tooth comes through. The important step is confirming that the swelling is truly eruption-related.

How long does an eruption cyst last?

It may be present for days or weeks, depending on how close the tooth is to emerging. A persistent or changing bump should be rechecked.

Can an eruption cyst become infected?

It is not an infection by definition, but any injured tissue can become irritated or contaminated. Pain, pus, fever, or spreading swelling are reasons to call promptly.

A practical next step

Short version: most of what parents notice turns out fine, and the rest is easier to handle early. Either way we're glad to check — call (201) 345-3637.

Sources

• American Academy of Pediatric Dentistry, Reference Manual of Pediatric Dentistry
• American Dental Association, MouthHealthy patient education
• American Association of Orthodontists, patient education