Dark knuckles: Causes, treatment, and prevention

Dark knuckles: Causes, treatment, and prevention

Dark skin patches on the knuckles are usual in those with darker skin tones. Anybody can develop dark knuckles though. Usually this symptom is harmless but it can sometimes indicate an underlying condition of health.

Dark patches of the skin are often caused by hyperpigmentation, which occurs when the skin produces more melanin than normal. Melanin is the pigment that gives color to the skin.

Dark knuckles often have no apparent cause. Nevertheless, dark knuckles for certain people, can be a result of a metabolic disorder, side effect of medication, or underlying disease.

We address some of the potential causes of dark knuckles, as well as therapies, home remedies, and whwn en to see a doctor in this article.

Causes of dark knuckles

Dark knuckles do not always have an obvious cause.
Dark knuckles do not always have an obvious cause.

Acanthosis nigricans

Acanthosis nigricans (AN) is a skin condition that causes small patches of skin to darken, thicken and become velvety to the touch, particularly near the knuckles. AN sometimes takes months or years to appear, and can cause a bad odor or itch to the skin.

Other areas where AN develops include:

Some people are more likely than others to get AN. These individuals include people who:

  • have overweight or obesity
  • are of Native American, African, Caribbean, or Hispanic descent
  • have a family history of AN

AN is not contagious or harmful on its own, but it can be a precursor to other medical issues, such as:

Prediabetes or diabetes

Darkening skin can mean that a person begins developing diabetes. Most of those at highest risk for AN often have a higher chance of diabetes.

Prediabetes means a person has higher blood sugar levels than normal. If a doctor may detect prediabetes early, a person can be able to prevent developing full diabetes by making lifestyle changes.

Hormonal conditions

AN may also indicate a thyroid or adrenal condition or a hormonal imbalance, such as PCOS. PCOS causes females to produce too much testosterone, resulting in problems of fertility, pelvic pain, acne, weight gain and menstrual irregularity.


If AN develops suddenly it can be a sign of cancer, especially stomach , liver or colon cancer.


Dermatomyositis is a rare disease that causes muscle weakness through inflammation of the chronic muscles. One of the first and most noticeable signs is a patchy bluish-purple or red rash that develops in areas of skin that cover near the joints. That involve the near-knuckle muscles, elbows, heels, and toes.

Other symptoms include:

  • muscle weakness and pain
  • deposits of calcium under the skin, called calcinosis
  • hard, painful nodules
  • unexplained weight loss
  • fever
  • inflamed lungs

Dermatomyositis is not curable, but early diagnosis may help relieve the symptoms and slow them down.

Addison’s disease

Addison’s disease is an autoimmune condition in which the body erroneously attacks the adrenal glands, leading to low cortisol and aldosterone levels.

An initial symptom of the addison’s disease is areas of darker skin near scars and creases of the skin, such as knuckles. This discolouration gives an early evidence that it can develop months or years before any other symptoms

  • fatigue
  • vomiting and, sometimes, diarrhea
  • nausea
  • abdominal pain
  • mood changes
  • irregular menstrual periods

A person with hormone replacement therapy can manage Addison’s disease to replenish cortisol and aldosterone in the body.

Vitamin B-12 deficiency

Dietary factors can lead to dark knuckles, too. A study from 2016 showed that knuckle pigmentation is an external sign of a deficiency in vitamin B-12. Other symptoms of a lack of vitamin B-12 include:

  • fatigue
  • weakness
  • constipation
  • loss of appetite
  • weight loss
  • numbness and tingling in the hands and feet

A person with a diagnosed deficiency of vitamin B-12 may adjust their diet to include more foods high in vitamin B-12 including:

  • fish
  • meat
  • poultry
  • eggs
  • milk

Vegetarians and vegans will possibly need to supplement their diet with vitamin B-12 supplements or fortified foods to satisfy their everyday needs.

Raynaud’s disease

The main symptom of Raynaud’s disease condition is the narrowing of blood vessels in the fingers or toes in response to stress or cold. This may trap blood in the fingers, causing blue discolouration.

Sometimes Raynaud’s disease occurs on its own, but it can also be a secondary symptom of another health condition, such as scleroderma or arthritis.

Drug reaction

One case study showed that specific drugs are more likely to cause hyperpigmentation than others. Such as:

If a person takes more than one type of drug, the medication is more likely to cause hyperpigmentation.


When a doctor identifies and prescribes medication for the root cause of dark knuckles, the discoloration should improve. If a drug causes the hyperpigmentation, a doctor may offer an alternative drug or dosage.

Home remedies can help lighten dark knuckles if there is no underlying cause or a doctor decides not to treat the hyperpigmentation.

Home remedies for dark knuckles

Although dark knuckles themselves do not require medical treatment, people who might want to try at-home treatments to lighten the dark knuckles may try:


Curcumin is an active Turmeric compound. A 2012 study found that the enzyme tyrosinase is disrupted by curcumin. This specific enzyme synthesizes melanin, so inhibiting melanin can help reduce skin darkening.

An individual may mix a small amount of water with this spice to use turmeric, and apply the paste for a few minutes to their knuckles.


A person may also use tea to lighten darker skin areas. A research carried out in 2015 found that one of the compounds in black, white and green tea — epigallocatechin gallate — also inhibits tyrosinase, thereby helping to lighten dark knuckles.

A person should steep a bag of tea in hot water, let it cool down, then soak a ball of cotton in the tea. We can apply the liquid several times a day to the knuckles.

Vitamin C

Vitamin C is an antioxidant which can help with a range of skin problems, including hyperpigmentation. Many marketable skin care products contain vitamin C.

Research indicates a concentration of 10–20 percent of the most powerful vitamin C products. Higher strengths do not increase the biological significance of the vitamin, and can cause irritation.

Alternatively, if a person would like to use an over-the-counter skin product, the American Academy of Dermatology recommends that they search for formulas which include:

  • 2% hydroquinone
  • azelaic acid
  • glycolic acid
  • kojic acid
  • retinoids (retinol, tretinoin, adapalene gel, or tazarotene)


Many of the underlying conditions that trigger dark knuckles are not preventable. A person may, however, help to prevent hyperpigmentation by using sunscreen before going out.

Avoid medications that cause hyperpigmentation may also help , but a person should talk to their doctor before stopping medication.

When to see a doctor

So even though darkening knuckles can indicate an underlying condition of health , it is important to see a doctor about sudden changes in this skin area. If a person has noticed other symptoms, then the cause will be found by a doctor.


Dark knuckles are usually not a cause of concern, and do not require treatment on their own. They are however, sometimes a sign of an underlying condition. Once a doctor determines whether a disease causes darkening of the skin, a person can take steps to deal with it.

Hyperpigmentation may improve the diagnosis of the underlying disease. If it persists, though, or there is no underlying condition to be treated, a range of home remedies and products can help people manage dark knuckles.