What Is a Gum Boil (Parulis)?
A gum boil, clinically known as a parulis, is a small swelling on the gum that resembles a pimple or blister. It typically forms as a result of an underlying dental infection—most commonly a dental abscess—creating a pathway through the gum tissue for pus to drain.
The boil develops when infection within a tooth or in the surrounding gum tissue produces pus that needs to escape. Rather than building up pressure within the bone, the pus finds a route through the gum, creating a visible bump. This is sometimes called a sinus tract or fistula.
Because the gum boil allows some drainage, it may actually reduce pain and pressure compared to an abscess that cannot drain. However, this does not mean the infection has resolved—the source of infection typically remains within the tooth or periodontal tissues and requires professional treatment.
Common Causes of a Gum Boil
Gum boils develop as a result of dental infection. Only a dental professional can identify the specific underlying cause through examination and imaging.
Tooth Infection or Dental Abscess
The most common cause is infection within a tooth that has spread to the root tip, creating an abscess that drains through the gum tissue.
Untreated Tooth Decay
Deep decay that reaches the nerve of a tooth can lead to infection, which may eventually manifest as a gum boil if left untreated.
Failed or Leaking Restorations
Old fillings, crowns, or other restorations that have begun to fail can allow bacteria to enter the tooth and cause infection over time.
Gum Disease (Periodontitis)
Advanced gum disease can create deep pockets around teeth where bacteria accumulate, potentially leading to periodontal abscesses that present as gum boils.
Previous Dental Trauma
A tooth that was injured in the past may develop infection years later, even if it initially seemed to heal without problems.
Root Canal Complications
In some cases, a tooth that has had previous root canal treatment may develop a new infection if the treatment was incomplete or the seal has been compromised.
Symptoms Associated with a Gum Boil
The symptoms of a gum boil may vary and can fluctuate over time. You may experience one or more of the following:
Raised Bump on the Gum
A small, pimple-like swelling on the gum tissue, often near the root of an affected tooth, that may appear red or yellowish.
Pus Discharge or Bad Taste
The boil may drain pus periodically, causing an unpleasant taste in the mouth. This drainage may provide temporary relief from pressure.
Swelling or Tenderness
The surrounding gum tissue may appear swollen, feel tender to touch, or look inflamed.
Toothache or Pressure
A dull ache, throbbing pain, or sensation of pressure in the affected area, particularly when biting or chewing.
Symptoms That Fluctuate
The boil may seem to come and go, becoming more prominent before draining and then appearing to settle—but the underlying infection typically persists.
General Discomfort
Some people experience a general feeling of being unwell, particularly if infection is more advanced. This warrants prompt professional assessment.
Why a Gum Boil Should Be Professionally Assessed
A gum boil is a sign that infection is present and ongoing. Even though the drainage it provides may reduce discomfort, the underlying infection will not resolve on its own—it requires professional treatment to address the source.
If the infection persists without treatment, it may gradually worsen or spread. In some cases, dental infections can spread to surrounding tissues, though this is less common when drainage is occurring. Nevertheless, the affected tooth typically continues to deteriorate without intervention.
Professional assessment focuses on identifying and treating the cause of infection, not just managing the visible symptom. This may involve examining multiple teeth, taking X-rays, and determining whether the problem originates from inside a tooth, from gum disease, or from another source.
How Dentists Diagnose a Gum Boil
Diagnosing the cause of a gum boil involves a thorough clinical examination and often dental imaging. Your dentist will:
- Examine the gum boil and surrounding tissues visually and by gentle probing
- Test the teeth in the area to identify which tooth may be the source of infection
- Take X-rays to visualise the roots of teeth and surrounding bone, looking for signs of abscess or bone loss
- Assess the health of your gums and check for signs of periodontal disease
- Review your dental history, including any previous treatment to teeth in the area
This comprehensive assessment allows your dentist to determine the most appropriate treatment approach based on the specific cause and extent of infection.
Professional Treatment Options for a Gum Boil
Treatment focuses on addressing the underlying cause of infection. Following assessment, your dentist may recommend one of the following approaches:
Root Canal Treatment
If the infection originates from within a tooth, root canal treatment removes the infected tissue and seals the tooth to prevent reinfection, often allowing the tooth to be preserved.
Drainage by a Dentist
In some cases, the dentist may drain accumulated pus to relieve pressure and discomfort, though this is typically combined with treatment of the underlying cause.
Tooth Extraction
If the tooth cannot be saved due to extensive damage or decay, extraction may be recommended to eliminate the source of infection.
Periodontal Treatment
If the gum boil is caused by gum disease, deep cleaning procedures or other periodontal treatments may be necessary to address the infection.
Antibiotics When Indicated
Antibiotics may be prescribed in certain situations to help manage infection, particularly if there is spreading or systemic involvement. However, antibiotics alone do not resolve the underlying cause.
Your dentist will discuss suitable options following examination, taking into account the source of infection and the condition of the affected tooth.
Professional Care for a Gum Boil
A gum boil requires professional dental assessment to identify and treat the underlying infection safely. Our dental team can examine the affected area, take appropriate imaging, and determine the most suitable treatment approach.
Depending on your needs, this may involve emergency dental assessment, root canal treatment to address infection within a tooth, or general dentistry services to manage the condition appropriately.
Assessment and treatment for gum boils are available at our London clinics. You can attend our South Kensington dental clinic or our City of London clinic near St Paul's for a professional dental assessment.
Can a Gum Boil Go Away on Its Own?
A gum boil may appear to come and go—draining periodically and then seeming to settle down. This can create the impression that the problem is resolving. However, this cycle typically indicates ongoing chronic infection rather than healing.
When the boil drains, pressure is relieved and symptoms may improve temporarily. But because the source of infection—usually within a tooth or in periodontal tissues—remains untreated, the infection continues. Pus will continue to form, and the boil will typically reappear.
Without professional treatment, this cycle can continue indefinitely. The affected tooth may gradually deteriorate, and in some cases the infection may cause progressive bone loss around the tooth root. For these reasons, professional assessment is recommended even if symptoms seem mild or intermittent.
Reducing the Risk of Gum Boils
While not all dental infections can be prevented, maintaining good oral health reduces the risk of developing conditions that lead to gum boils:
- Attend regular dental check-ups to detect and treat problems early
- Seek treatment for tooth decay before it reaches the nerve
- Maintain good daily oral hygiene with twice-daily brushing and flossing
- Have failing or aging dental restorations reviewed and replaced when needed
- Address gum disease promptly with professional treatment
- Report any ongoing toothache or gum symptoms to your dentist
