The skin on the neck is prone to darkening, whether due to hormones, sun exposure, or other skin-related conditions. A person whose neck darkens or turns black may also notice changes to the texture of their skin, such as thickening or feeling softer than the surrounding skin.

While most causes of a black neck are not medical emergencies, it is always best to see a doctor for a proper diagnosis.

In this article, we look at the possible causes of a black neck, as well as the treatment options.

Causes

Acanthosis nigricans can cause black neck
Acanthosis nigricans can cause dark, thick skin on the neck.
Image credit: Vandana Mehta Rai MD DNB, C Balachandran MD (2010, March 14).

Possible causes of a black neck include:

Acanthosis nigricans

Acanthosis nigricans can cause dark, thick skin on the neck. The skin may have a similar texture to velvet.

This condition can appear suddenly, but it is not contagious nor does it present a danger to a person’s health.

People who are obese and those with diabetes are at greater risk of the condition.

In rare instances, acanthosis nigricans can indicate a more serious underlying medical condition, such as stomach or liver cancer.

Dermatitis neglecta

Dermatitis neglecta is a skin condition that occurs when a person has a buildup of dead skin cells, oil, sweat, and bacteria on their skin. The buildup of debris causes discoloration and skin plaques.

The neck is a common place for dermatitis neglecta to develop, often because of insufficient cleansing with soap, water, and friction to remove excess skin cells.

Dyskeratosis congenita

Also known as Zinsser-Engman-Cole syndrome, dyskeratosis congenita causes hyperpigmentation of the skin of the neck. The neck may look dirty.

In addition to dark patches on the neck, the condition can cause white patches inside the mouth, ridging of the fingernails, and sparse eyelashes.

Erythema dyschromicum perstans

Erythema dyschromicum perstans, or ashy dermatosis, causes slate-gray, dark blue, or black irregularly-shaped patches of skin on the neck and upper arms. Patches can sometimes appear on the torso.

The condition is benign and does not indicate any underlying medical conditions.

High blood insulin levels

When a person has chronically high insulin levels, they can experience areas of hyperpigmentation on the neck, especially on the back of the neck. This occurrence is common in women who have polycystic ovary syndrome (PCOS).

Lichen planus pigmentosus (LPP)

LPP is an inflammatory condition that causes scarring to develop on areas of the body. Symptoms include grey-brown to black patches on the face and neck. The patches are not itchy.

Tinea versicolor

Tinea versicolor is an infection of the fungus Mallassezia furfur. While this type of yeast is naturally present on the skin, too much of it or an overgrowth can cause dark patches on the neck, back, chest, and arms.

The skin may appear especially dark if a person has recently been exposed to the sun. The skin patches may also itch.

Diagnosis

Analyzing a patient for black neck
A doctor may take a skin sample while inspecting the neck.

A doctor will diagnose the cause of a black neck by asking a person about their medical history and any recent changes to medications or lifestyle habits, such as sun exposure.

They will visually inspect the neck and may refer the person to a dermatologist if the cause is not clear.

A doctor may also perform some of the following tests to determine a potential underlying cause:

  • Blood tests: A test may be carried out for blood sugar or hormone levels.
  • Skin sample: A skin scraping or biopsy may be done to determine if fungal cells are present.

Treatment

Once a doctor determines the cause of black neck, they will recommend condition-specific solutions.

Treatments for each of the above condition may include:

  • Tinea versicolor: A doctor will usually treat fungal infections with antifungal ointments that can be applied to the skin. Severe cases may require oral anti-fungal medications.
  • Dermatitis neglectans: Scrubbing with soap and water can often reduce the appearance of a black neck from dermatitis neglectans. A person may wish to soak the neck in a bath or apply a hot compress to loosen stubborn debris.
  • Acanthosis nigricans: While there are skin-lightening creams and scrubs that promise to reduce skin darkening associated with acanthosis nigricans, these are usually ineffective. Addressing the underlying causes may help, such as managing blood sugar levels and losing weight.
  • Hyperpigmentation: Treatment for hyperpigmentation may include topical tretinoin, a form of retinoic acid that encourages skin cell turnover. Laser therapies may also help to reduce the incidence of hyperpigmentation.

Other treatments will depend upon a person’s underlying condition and overall health.

Home remedies

Exfoliating scrubs can help black neck
Exfoliating scrubs can help reduce black neck by removing dead skin.

Positive skincare and lifestyle habits may help to reduce the incidence of a black neck. A person can take preventative steps by:

  • washing the skin with soap and water twice daily
  • using exfoliating scrubs to help get rid of dead skin
  • applying sunscreen daily
  • eating a healthful diet with plenty of fruits and vegetables

Many companies claim their products can help lighten the skin, but research has found that there is no conclusive evidence to support the effectiveness of the following ingredients:

  • arbutin
  • azelaic acid
  • kojic acid
  • licorice
  • mulberry
  • turmeric
  • vitamin C

However, it is possible that applying products at home could provide some results. A person should always apply a new product to a small area or test patch first and wait 24 hours to ensure they are not allergic or sensitive to the substance.

Outlook

A black or hyperpigmented neck can be troubling, but it is often treatable. If a person is unsure of the cause of black neck or is having symptoms, such as itching and pain, they should see their doctor for a proper diagnosis.