Black spots inside the cheek can have several causes. These include blisters or hyperpigmentation. In rare cases, they may indicate mouth cancer.

Depending on the cause, the black spot may resolve without treatment. However, if it does not go away, or if it keeps coming back, it is important to contact a doctor for an accurate diagnosis and, where necessary, suitable treatment.

Read on to learn more about the potential causes of a black spot inside the cheek. This article also discusses some treatment options, and when to contact a doctor.

Blisters are raised bubbles on the skin with fluid inside. They can occur anywhere on the body, including in the mouth.

Blood blisters contain blood and appear dark red or purple. They may develop in the mouth due to accidentally biting the cheek or as a result of an allergic reaction.

Learn more about blood blisters in the mouth.

Treatment

Blood blisters are not typically harmful, and they will often heal without treatment.

Sometimes, however, they may cause pain or discomfort. In these cases, a person can use over-the-counter (OTC) pain relief medication.

Amalgam tattoos occur when metal fillings leak, causing dark marks to appear inside the mouth.

These marks can appear when a dentist places or removes a filling and tiny metal fragments fall between the teeth.

They most commonly appear on the gum or cheek near the amalgam filling. However, they can appear anywhere in the mouth.

Treatment

Amalgam tattoos do not cause any symptoms or require any form of treatment. However, if it is visible on a person’s lip, they may wish to discuss with their doctor the possibility of removal for cosmetic reasons.

Smoking can cause a smoker’s melanosis. This is a condition wherein brown or black pigmentation develops inside the mouth and throat.

Treatment

Smoker’s melanosis does not require treatment. It should disappear within 6 to 36 months after quitting smoking.

If a person wishes to treat the condition for aesthetic purposes, laser treatment may help.

Melanoma is a cancer of the pigment-making cells, or melanocytes, that typically affects the skin. However, these cancers can also occur on mucosal membranes, such as in the mouth.

Oral melanoma is a rare condition that can appear as a raised area with a black, brown, or dark blue appearance. These marks can be asymmetric with an irregular border.

There may also be swelling if inflammation is present.

A 2023 article notes that oral melanoma is not related to sun exposure. Healthcare professionals are unsure about what the risk factors are, but they may include:

  • dental irritation
  • cigarette smoking
  • alcohol consumption

Learn more about oral cancer.

Treatment

The main treatment option for oral melanoma is surgery. A healthcare professional may also recommend radiation therapy.

Addison’s disease is an endocrine disorder that occurs when the adrenal glands, the glands on the top of the kidneys, do not make enough of certain hormones. These include cortisol and aldosterone.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) notes that Addison’s disease can cause the development of darker areas on the skin and inside the mouth.

Other symptoms can include:

Learn about what can cause Addison’s disease.

Treatment

Treatment for Addison’s disease will include hormone replacement medications. People can take a corticosteroid, such as hydrocortisone, to replace missing cortisol. They will take an oral tablet 2 or 3 times per day.

To replace aldosterone, a person can take fludrocortisone to help balance the amount of fluid and sodium in the body.

Peutz-Jeghers syndrome is a rare genetic condition that causes dark freckles to appear around the face and inside the mouth. It may also cause mushroom-shaped tissue growths called polyps to develop throughout the gastrointestinal tract.

Peutz-Jeghers syndrome can also cause other symptoms, including:

Treatment

There is currently no cure for Peutz-Jeghers syndrome. However, treatments may involve surgically removing any polyps that are causing gastrointestinal problems.

A doctor or dentist will perform a physical examination of the black spots to help determine the cause. They will likely ask the person whether or not the spots are painful or have any accompanying symptoms.

A doctor may also check a person’s medical history for any signs of genetic conditions that could be the cause. They might also review the person’s dental records for the presence of metal fillings.

Depending on their assessment, a doctor may also order additional tests to make a firm diagnosis. For example, they might require a blood test or skin sample for further analysis.

The doctor can advise on what tests they recommend, and answer any questions a person may have.

Although medical treatment may not be necessary for some causes of a black spot in the cheek, a person should contact a doctor about any sore or spot that does not go away or that keeps coming back.

If the black areas develop sores or ulcers, these could be symptoms of mouth cancer. Oral cancer also has a high risk of recurrence, so it is essential to contact a doctor about a black spot if a person has previously had an oral cancer diagnosis. Early detection of mouth cancer is crucial for successful treatment.

There are many possible causes of black spots inside the cheek. These include blood blisters, amalgam tattoos, smoking, Addison’s disease, and Peutz-Jeghers syndrome. In some cases, it can indicate oral cancer.

Some people may require OTC treatments for causes that cause pain, such as blood blisters. Other causes, such as mouth cancer, will require medical treatment.

A person should contact a doctor about persistent cases. They can help determine the underlying cause, and advise on suitable treatments if necessary.