Black Spot Inside Cheek: Causes, When to Worry, and Treatments

Noticing a new black or dark spot on the inside of your cheek can be unsettling. While your mind might jump to the worst-case scenario, it's important to know that most of these spots are completely harmless. They can result from something as simple as accidentally biting your cheek or from previous dental work.

However, in rare cases, a dark spot can be a sign of a more serious condition. This comprehensive guide, informed by medical research and expert sources, will walk you through the potential causes, help you identify warning signs, and explain when it's time to see a doctor or dentist for a professional diagnosis.

Common Harmless Causes of Black Spots Inside the Cheek

Most oral discolorations are benign. Here are the most frequently seen causes for a black spot inside the cheek, most of which do not require treatment.

Trauma and Injury

Your mouth is a busy place, and minor injuries are common.

• Blood Blisters: Accidentally biting or pinching your cheek can cause a blood blister to form. This is a raised sac filled with blood that appears dark red, purple, or black. While they can be tender, they typically heal on their own within a week or two.
• Bruising: A minor injury can cause a small bruise (hematoma) on the soft tissue of your cheek, which may look like a dark spot as it heals.

Pigmentation and Moles

Just like your skin, the tissue inside your mouth contains pigment-producing cells (melanocytes).

• Oral Melanotic Macule: This is a harmless, flat spot, similar to a freckle, caused by an increase in melanin. These macules are well-defined, usually smaller than a pencil eraser, and do not become cancerous.
• Oral Nevi (Moles): It's also possible to have a common mole (nevus) inside your mouth. These are typically small, slightly raised, and can be brown, bluish-gray, or almost black. While oral nevi are almost always benign, a dentist may recommend a biopsy to confirm the diagnosis.

!An image of an oral melanotic macule, a harmless freckle-like spot, on the inside of a person's mouth. An oral melanotic macule is a common, benign pigmented spot, similar to a freckle, that can appear inside the mouth. Image Source: ResearchGate

Stains from External Sources

Sometimes, the spot is caused by a foreign substance embedded in the tissue.

• Amalgam Tattoos: This is one of the most common causes of a dark spot in the mouth. It occurs when a small particle from a silver-colored (amalgam) dental filling gets lodged in the soft tissue of your cheek or gums during a dental procedure. The result is a permanent, painless blue, gray, or black flat spot that is completely harmless.
• Graphite Implantation: If you've ever chewed on a pencil, it's possible for a piece of graphite to have become embedded in your cheek lining, creating a small, dark tattoo. This is also benign.
• Smoker's Melanosis: Tobacco use can stimulate melanin production, leading to brown or black blotchy patches inside the cheeks and on the gums. According to a study in Case Reports in Dentistry, this condition is found in about 22% of smokers. While the spots themselves are not harmful, they are a sign of tobacco use, which is a major risk factor for oral cancer. The pigmentation often fades after quitting smoking.

When a Black Spot Could Signal a Health Condition

Though much less common, a black spot inside the cheek can sometimes be an oral manifestation of an underlying medical issue or, very rarely, a sign of cancer.

Systemic Diseases with Oral Symptoms

Certain systemic diseases can cause hyperpigmentation in the mouth.

• Addison's Disease: This rare disorder occurs when the adrenal glands don't produce enough of certain hormones. A key symptom can be the darkening of the skin and mucous membranes, including blotchy, dark patches inside the cheeks. Other symptoms include fatigue, weight loss, and muscle weakness.
• Peutz-Jeghers Syndrome: This is a rare genetic condition that causes dark blue or brown freckle-like spots to appear around the mouth, on the lips, and inside the cheeks, often during childhood. People with this syndrome also develop noncancerous polyps in their digestive tract, which increases their lifetime risk of certain cancers.

Oral Cancer (A Rare but Serious Cause)

In extremely rare cases, a black spot can be a sign of oral melanoma. Oral melanoma is an aggressive cancer that affects the pigment-producing cells in the mouth. It accounts for less than 1% of all melanomas, according to The Oral Cancer Foundation.

Early oral melanoma might appear as a dark brown, blue-black, or even white spot. In later stages, it can become raised, bleed, or form an ulcer. Because it is so rare and dangerous, any new or changing pigmented lesion in the mouth needs to be evaluated by a professional.

Visual Guide: Benign vs. Potentially Concerning Spots

While only a doctor can provide a diagnosis, you can look for certain characteristics.

Feature	Usually Benign Spot	Potentially Concerning Spot (See a Doctor)
Border	Smooth, even, well-defined	Irregular, notched, or blurry
Color	Uniform color (one shade of brown, gray, or blue)	Multiple colors (shades of black, brown, blue, red)
Size/Shape	Stays the same size and shape over time	Changes in size, shape, or thickness
Surface	Flat or slightly and smoothly raised	Becomes raised, bumpy, rough, or ulcerated (sore)
Symptoms	Painless, no bleeding	Becomes painful, tender, itchy, or bleeds easily
Healing	A blood blister will heal within 2 weeks	A sore or ulcer that does not heal within 2 weeks

When to See a Doctor or Dentist

It's always best to err on the side of caution. Schedule an appointment with your dentist or doctor if you notice a black spot inside your cheek, especially if:

• It's new and you don't know what caused it.
• It changes in size, shape, color, or texture.
• It has an irregular border or multiple colors.
• It bleeds, is painful, or feels rough.
• It appears as a sore that doesn't heal within two weeks.
• You have other concerning symptoms like unexplained weight loss or fatigue.

Diagnosis and Treatment

To determine the cause of the spot, a healthcare professional will:

1. Perform a Visual Examination: They will carefully examine the spot's location, size, color, and texture.
2. Review Your Medical and Dental History: They will ask about your smoking habits, medications, and any past dental work, like amalgam fillings.
3. Perform a Biopsy: If cancer is a possibility, the doctor will remove a small sample of the tissue for analysis in a lab. This is the only way to definitively diagnose or rule out oral cancer.
4. Order Blood Tests: If a systemic condition like Addison's disease is suspected, blood tests may be ordered to check hormone levels.

Treatment depends entirely on the diagnosis:

• Benign Lesions: Most harmless spots, like amalgam tattoos and melanotic macules, require no treatment at all.
• Blood Blisters: These heal on their own.
• Smoker's Melanosis: The main recommendation is to quit smoking.
• Systemic Diseases: Treatment will focus on managing the underlying condition (e.g., hormone replacement therapy for Addison's disease).
• Oral Melanoma: Treatment is urgent and may involve surgery, radiation therapy, and/or immunotherapy. Early detection is critical for a better outcome.

References

• Medical News Today - Black spot inside cheek: Pictures, causes, treatment, and more
• Healthline - Possible Causes of a Black Spot Inside Your Cheek
• Colgate - Causes Of A Black Spot Inside The Cheek
• Mayo Clinic - Mouth cancer
• The Oral Cancer Foundation - Oral Malignant Melanoma
• Case Reports in Dentistry - Smoker's Melanosis