Gum Boil – An Innocent Pimple On The Gums?

Written & Reviewed by Dr David Chen

Is there a gum boil in your mouth? It may look like an innocent pimple on the gums but the truth is, its far more serious than that. You should seek out a consultation with your dentist as soon as possible.

Let us explain why a gum boil is an urgent dental condition. It is also sometimes known as a parulis.


A gum boil may look like a pimple on the gums but it is actually the orifice of a sinus tract that leads to a periapical abscess.

tooth abscess

How it forms is when the abscess is left untreated, it begins to grow in size until it eats through the jaw bone. Eventually the infection causes enough destruction to create a tunnel between where the tooth is located to the gums.

That tunnel is what we call a sinus tract. The pimple on the gums is the abscessed part that is literally open and connects directly to the abscessed tooth.

Therefore you can think of a gum boil as an oral manifestation of a tooth abscess. It is literally an extension of the periapical abscess. However you should be aware that not all of these infections form a pimple on the gum.


Since a gum boil is technically an extension of a periapical abscess, the signs and symptoms would be similar to one.

  • Toothache. Tooth pain that may be be constant or it comes and goes. The pain can feel sharp, shooting or dull. It can also throb and radiate across your entire face.
  • Painless. Yes, this condition CAN be non-painful as strange as that may sound.
  • Swelling. Gums or area around the tooth are swollen.
  • Purulence. If you squeeze the gum boil, a white fluid will ooze out. That is pus.
  • Loss of sensitivity. When an abscess forms like this, the tooth has already died.
  • Pimple on the gums. An innocent looking pimple on your gums next to your tooth.
  • Chewing pain. When you’re eating, it hurts to bite down.
  • Fever. A fever can potentially develop if the infection gets severe enough.
  • Foul odor. Bad taste or bad smell coming from your mouth.
  • Loose tooth. Abscessed teeth will often feel mobile and loose. You can even wiggle it.

As an additional emphasis, there are many times where having a gum boil can be painless, especially if it pops. The reason why you’ve a lot of pain before it pops is that you feel the abscess building up pressure inside of the jaw bone.

However once the pimple pops, all of that pressure in the jaw bone gets released. Since the gum boil has popped and is now actively draining, there will be no more pain

When to see a dentist

If you have a pimple on the gums, you need to see a dentist pronto. No ifs, buts, or whats. That includes if you think you have one after a tooth extraction.

Just to reiterate, this condition is a true dental abscess and that means you need to get it treated promptly. You cannot and should not delay treatment for an infection!


A gum boil can usually be diagnosed with high confidence via a visual examination. However, an x-ray along with gutta percha tracing will confirm the diagnosis.

X-ray of a gum boil

Typically by the time a gum boil forms, it means the abscess has destroyed enough of your jaw bone to show up on the x-ray. If you take a PA radiograph, you’ll see a large radiolucent area around the root tip of the infected tooth.

front-tooth-periapical-pathology - marked
Periapical abscess outlined on x-ray

A radiolucent object inside of a radiopaque object implies that it is becoming less solid. That is consistent with the definition of a periapical abscess where the infection is destroying bone. In other words, there is less bone because there is a hole in the jaw bone!

Gutta percha tracing

If the gum boil is located in an ambiguous location such as in between teeth, it may be difficult to ascertain which tooth is the abscessed one. Using a technique called gutta percha (GP) tracing can help identify the source of the infection and which tooth it is coming from.

What to expect during GP tracing:

  1. Your dentist will insert a gutta percha directly into the gum boil.
  2. They will push it as far in as they can.
  3. Take a PA x-ray and the GP should lead straight to the abscessed tooth.
x-ray of gutta percha tracing
Gutta percha tracing

Note: The fact that gutta percha tracing works, is evidence that a gum boil is literally the opening of a sinus tract that leads directly to a periapical abscess!


The gum boil is an oral manifestation of a periapical abscess but we should explain from the beginning of how it forms.

  1. Untreated tooth decay will grow and progress through the enamel, dentin, and pulp.
  2. After the pulp gets infected, the bacteria will travel straight down the canal to the tooth root where it forms an abscess.
  3. The abscess expands and expands until it destroys enough jaw bone to puncture a hole through the gums.
  4. That opening in the gums is what you see as a gum boil.

Alternative cause

Tooth decay is one of the most common reasons for developing a pimple on the gums. However there are two other conditions which may result in a gum boil forming.

  • Re-infected root canal. Teeth that have been root canal treated can get re-infected once more. A tell-tale sign of that is a gum boil forming despite having a root canal. Treatment for this would require a root canal retreatment.
  • Re-infected root canal retreatment. Yes, even teeth that have been retreated by root canals can get infected once more. Once again, a pimple will form on the gums.
  • Re-infected apicoectomy. The apicoectomy that is used to treated a failed root canal retreatment can also get infected. Guess what you’ll expect to see, a gum boil.
  • Fractured tooth. A tooth that has an external or internal fracture can develop a pimple on the gums. If this is the case, the entire tooth will need to be extracted.
CBCT of fractured tooth with halo

The image above is a CT scan showing a tooth with a root canal but has developed a fracture, denoted by the arrow on the bottom right photo. Fractured teeth are non-restorable.


Teeth with a gum boil for the first time can usually be treated with a root canal. By removing the infected nerve, which is the source of the infection, the pimple should resolve within a week after treatment.

Antibiotics are typically unnecessary as long as there is no diffuse facial swelling. Completing the root canal procedure is more than sufficient in clearing out the infection.

However for teeth that develop it for the second time, it may be a recurrent infection or a fracture inside of the tooth. If it is the former, you can try a root canal retreatment but for the latter, it will be a tooth extraction.

At home treatment

It is impossible to treat a gum boil at home because popping it is NOT considered the complete treatment. Popping the boil may relieve pressure and offer you pain relief but it does NOT address the source of the infection.

As we explained above, proper treatment requires either a root canal or a tooth extraction. Those are the only two ways to remove an infected nerve from within the tooth. We didn’t even mention popping it as part of the treatment because the gum boil dissipates on its own after extirpating the infected nerve.

Gum boils tend to pop on their own

With that being said, most gum boils tend to pop on their own while you’re eating or brushing. Although we don’t recommend intentionally trying to do it yourself.

Your fingers aren’t always the cleanest tool so if you try to drain it, you may introduce new bacteria into it. Aside from that, it can be painful attempting to squeeze the pimple without any anesthetic.

Typically, most of the boils will pop on their own. Since it is filled with pus and other fluids, it is literally like a full balloon. That makes it prone to getting nicked while you’re eating or brushing, which will accidentally pop it. What you’ll notice is a sudden bad taste of drainage in your mouth since pus will be oozing out.

When will it go away?

After getting treatment for it, it should go away within 1-2 weeks. That is simply how long it takes your body to heal and recover from the infection. If you don’t get it treated, the boil may last forever.


The best way to prevent a gum boil is by getting treatment early whenever a dental problem arises. The boil is a late stage oral manifestation of an abscess but prior to that it is simple tooth decay. The moral of the story is to get your cavities treated as early as possible because it would be just a dental filling.


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