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Teething can be tougher for some babies — and parents — and easier for others. Either way, you’ll likely see some of the usual signs that your little one is about to have their first tooth milestone.

For example, your baby might:

  • be very grumpy and clingy
  • drool more than usual
  • gnaw on anything within reach
  • rub their ears a lot

Some babies may also have less common signs of teething, like eruption cysts. These little bubbles or bumps on a baby’s gums might look strange — even alarming — but they’re generally harmless and go away quickly.

These cysts are more common in older children who are getting their adult teeth in, but it’s possible for babies to get them as well.

Here’s what to know about this rare teething side effect on your baby’s gums.

Also called a congenital eruption cyst or an eruption hematoma if the fluid it’s filled with is mixed with blood, an eruption cyst in a teething baby is kind of what it sounds like.

It happens when a brand new tooth is trying to grow and poke out of a baby’s gums. Sometimes, a small fluid-filled swelling, sac, or bubble forms. This can occur on top of the gums or just under the gum surface over the growing — or erupting — tooth.

The new tiny pearly white will still poke out through the eruption cyst, and the cyst usually goes away on its own without treatment.

An eruption cyst might sound painful — and it can make baby’s gums tender — but it typically won’t hurt.

If your little one has an eruption cyst, you may notice a small bluish, yellow, white-tinged, or clear dome or bubble sitting on their gums.

This soft tissue sore will be just over the growing tooth and might feel similar to a squishy, balloon-like bump. The gums around the eruption cyst might also be a little swollen, irritated, or red.

Most eruption cysts are under a half-inch in size. Your baby might have just one eruption cyst, or they could have more than one at a time.

Sometimes the fluid inside the eruption cyst is mixed with a little bit of blood. When this happens, it might look more pink, red, or purple in color.

Don’t worry — the blood doesn’t mean the eruption cyst is getting worse.

An eruption cyst happens when fluid collects in the space around a tooth that’s about to erupt, or come through, the gums. You might notice one when your baby is teething, but before you can actually see the new tooth.

Eruption cysts can sometimes happen for reasons that aren’t clearly understood. They may include inflammation or trauma. Other causes are irritation or an infection in baby’s gums.

In still other cases, there may be overcrowding in the gums when two teeth are growing next to each other. This can raise the risk of an eruption cyst in a teething baby, though overcrowding is more common in older children getting their permanent teeth.

A small trauma or injury to the gums can also lead to an eruption cyst. This can happen accidentally when your baby is chomping on a teething toy.

Some babies and toddlers might have eruption cysts because of dental decay.

How common are eruption cysts?

Eruption cysts aren’t common in babies.

Older children under age 10 also get eruption cysts. In fact, they’re most common in kids ages 6 to 9 years who are getting in their first adult molars.

In most cases, your baby won’t need any treatment for an eruption cyst. They usually go away on their own after the tooth grows and pushes — or just pops harmlessly — through it.

In some cases, a slow-growing or impacted (stuck) tooth will mean that an eruption will last for a long time. If this happens, your pediatrician or pediatric dentist will monitor it regularly and wait for a few weeks to months.

On an X-ray, fluid in an erupted cyst will look like a dark shadow around a new tooth under the gums.

In rare cases, your pediatrician or pediatric dentist might be needed if the eruption cyst is blocking the tooth from growing properly. Treatment includes removing dense or fibrous tissue to help the tooth grow properly.

Another kind of treatment is “unroofing,” or opening the top of the eruption cyst to free the tooth. Surgical treatment for an eruption cyst is very rare in babies, however.

In most cases, an eruption cyst will go away in a matter of days or weeks — as soon as the tooth grows above the gum line. In some cases, if the tooth is growing slowly or impacted, the eruption cyst may last for up to 4 months.

Let your pediatrician or pediatric dentist know if an eruption cyst lasts longer than a couple of weeks or if you notice anything else unusual on your baby’s gums. Contact your pediatrician if you see any bleeding or white pus on the gums.

Dental health is important at every age — even babies can get cavities. Make sure your baby sees a dentist for a regular dental checkup before they’re 2 years old.

Before your baby even has teeth, gently clean their gums regularly with a soft, sterile washcloth. Once their tiny new teeth come in, you can use a soft-bristle toothbrush designed for babies.

Eruption cysts are typically harmless fluid-filled bubbles on the gums that can sometimes happen when your baby is teething.

They’re rare in babies, though, and more common in young children growing in their adult teeth.

Eruption cysts typically go away on their own without treatment. Let your pediatrician know if your baby has an eruption cyst that doesn’t go away or if it bleeds or looks infected.