Eruption Cyst on a Baby's Gums: What to Do

What Is an Eruption Cyst on a Baby’s Gums?

An eruption cyst is a small, harmless bluish bump that forms on a baby’s gum right before a tooth comes through.¹ Most clear on their own within a few days to weeks as the tooth emerges, and they rarely need treatment. Call your pediatric dentist if the bump looks infected, lasts more than a few weeks, or makes feeding painful.¹

Eruption cysts (also called eruption hematomas) are fluid-filled sacs that sit over an erupting tooth.² They appear as a rounded, translucent dome — usually bluish-purple, sometimes reddish-brown if there’s blood in the fluid.^1,3 The cyst is most common in babies cutting their first teeth and in children whose permanent molars are coming in.³

What to Do If You See One

• Watch and wait — Most eruption cysts disappear on their own within a few days to weeks as the tooth pushes through.¹
• Don’t poke or pop it — Trying to burst the cyst with fingers or objects can introduce bacteria and cause infection.¹
• Keep the area clean — Wipe your baby’s gums with a soft, damp cloth at feeding times.⁶
• Call the dentist if — The bump lasts more than two weeks, looks infected (red, swollen, pus, or fever), or makes your baby refuse to feed.^1,5

Symptoms of an Eruption Cyst

The cyst usually appears as a single rounded swelling over the spot where a tooth is about to come through.³ Beyond the visible bump, most babies have no other symptoms — the cyst often causes no pain at all.^1,3

Some children feel mild tenderness or fussiness during feeding, especially if the cyst sits over a molar. Bleeding inside the sac can turn the dome darker, but a deep purple color alone is not a sign of trouble.¹

What Causes an Eruption Cyst?

A tooth pushing up through the gum is the trigger. Fluid — sometimes mixed with blood — collects between the gum tissue and the crown of the erupting tooth, forming a soft sac on the surface.² The cyst usually shows up shortly before the tooth breaks through and disappears once the tooth emerges.¹

Eruption cysts are most often seen in two age windows: babies cutting their first (primary) teeth, which start coming in around 6 months and continue through about age 3, and children whose permanent molars are erupting between roughly age 6 and 12.⁴ They can appear on either the upper or lower gums, and where the cyst sits doesn’t tell you whether it’s serious.³

They also show up occasionally in:

• Newborns whose teeth erupt earlier than expected¹⁰
• Adolescents with emerging wisdom teeth (third molars)³

What Does an Eruption Cyst Look Like?

An eruption cyst is typically bluish-purple.¹ It might appear reddish-brown if the fluid in the sac mixes with blood.

It’s a translucent dome of soft tissue that overlays an erupting tooth.² Some look more like a small bruise than a bump.

Eruption Cyst Treatment

Eruption cysts are left alone in nearly every case — they burst on their own once the tooth emerges, usually within a few days to weeks.^1,2

If a cyst lasts longer than two weeks, looks infected, bleeds, hurts, or makes feeding hard, have a pediatric dentist take a look.^1,2 If treatment is needed, the dentist may open the cyst to drain the fluid and expose the tooth. Anesthesia or sedation choices depend on your child, and recovery is usually quick.³

If there are signs of infection — pus, fever, swelling that spreads beyond the cyst — the dentist will evaluate the area and recommend treatment.¹

Eruption Cysts vs. Other Oral Cysts

Eruption cysts are the soft-tissue variant of dentigerous cysts — cysts that form because of tooth development.^2,8 Don’t confuse them with mucoceles (oral mucous cysts), which form on the inner lip or cheek when a small salivary gland gets blocked, often from biting or lip-sucking.⁷ Mucoceles look similar to eruption cysts but appear on soft tissue, not over an erupting tooth.

Dentigerous cysts are among the most common jaw cysts in children, but eruption cysts are easier for parents to spot because they show on the gum surface.⁹

Outlook and Complications

An eruption cyst can become infected if bacteria get inside the sac. Signs include increasing pain, redness, swelling that spreads, pus, or a fever — all reasons to call your pediatric dentist the same day.¹

Don’t poke or prod at the cyst. Trying to burst it with fingers or objects can break the surface and let bacteria in.¹

Can You Prevent Eruption Cysts?

You can’t really prevent an eruption cyst — it’s part of how some teeth come in. What you can do is lower the risk of infection in an existing cyst: keep your baby’s gums clean by wiping them with a soft, damp cloth at feeding times, and switch to a soft-bristled brush once teeth appear.⁶

When to See a Pediatric Dentist

Call your pediatric dentist if the bump on your child’s gums:^1,5

• Lasts more than two weeks without a tooth emerging
• Looks infected (red, swollen, pus, fever)
• Makes feeding painful or causes your baby to refuse feeds
• Bleeds without obvious cause
• Appears with broader symptoms like persistent fussiness or facial swelling

The American Academy of Pediatric Dentistry recommends a first dental visit by your child’s first birthday or within six months of the first tooth emerging.⁵ If you haven’t established a dental home yet, an eruption cyst is a reasonable reason to schedule that first visit.