Do the dark patches on your knuckles bother you? While people of any age can develop these, it is more prevalent among those with a darker skin tone.
While dark knuckles are harmless by themselves, these may indicate an underlying health condition that you may be having. So, let us explore what can be the probable causes, treatments and some home remedies.
What Causes Dark Knuckles?
Being one of the most exposed parts of the skin, knuckles also undergo constant friction. This along with a range of internal and external factors, may lead to hyperpigmentation of the knuckles. There is an overproduction of melanin, the pigment that gives your skin its natural colour.
Dark knuckles may be hereditary in nature. They may also be caused as a side effect of certain medications or skin care products. Additionally, they can also indicate the presence of a metabolic disorder or an underlying health issue, which if diagnosed early can be treated easily.
A few conditions that might be the reason behind dark knuckles are elaborated below.
1. Acanthosis Nigricans (AN)
This condition causes thickening and darkening of patches of skin over different joints and folds in the body including the knuckles. Acanthosis nigricans can affect people of all ages, and is more prevalent in the African, Caribbean, Hispanic and native American populations.
While usually harmless by itself, AN is not infectious. The darkened patches of skin usually stay soft to touch and appear velvety. Some patients may develop a mild itchiness in the affected areas.
However, AN can indicate the presence of other health issues such as diabetes, hormonal imbalances or cancer. Children with AN often also have excessive body weight, higher levels of insulin or diabetes.
A study in a patient cohort aged between 7 to 65 years, found a high association of AN with type 2 diabetes and its risk factors such as high insulin levels or insulin resistance.  AN can also be hereditary, or in rare cases, be a side effect of contraceptives or cholesterol medications.
2. Vitamin B12 Deficiency
Darkening of knuckles can be an important external marker indicating vitamin B12 deficiency, which is otherwise not so easily detectable. In a 2016 case study, the presence of dark knuckles, along with pallor and tiredness led to the diagnosis of vitamin B12 deficiency.
Vitamin B12 containing compounds, also known as ‘cobalamins’, are essential for the synthesis of red blood cells, nerve cells and DNA. Deficiency in vitamin B12 can lead to megaloblastic anemia and neurological disorders, if left untreated.
Knuckle hyperpigmentation due to vitamin B12 deficiency is usually reversible. Upon correcting this deficiency, the darkening of knuckles also disappears. Vitamin B12 is naturally present in animal based food products like meat, fish, poultry, dairy etc. Vegans and vegetarians must opt for foods fortified with vitamin B12 or add a dietary supplement, as recommended by the doctor.
Dark patches of skin on the knuckles and other body parts may signal the development of diabetes, even before the disease has set in. Prediabetes is a condition where you have higher than normal blood sugar levels, but there may be no other symptoms.
Knuckle hyperpigmentation can be a foreteller of diabetes. If diagnosed early, it can be managed better with lifestyle changes or medications, as deemed suitable by the healthcare professional.
In patients already diagnosed with diabetes, dark knuckles can indicate that the disease is not being optimally managed. Adjustments in treatment strategies can help regulate diabetes better.
PCOS or polycystic ovarian syndrome arises due to the imbalance between female and male hormones in women of child-bearing age. Presence of dark patches of skin on joints and creases adds to plethora of other symptoms.
PCOS is often associated with insulin resistance. Therefore, reducing weight and incorporating a healthy lifestyle may help manage the symptoms better.
5. Autoimmune Disorders
Autoimmune disorders occur when your own immune system starts attacking the very cells and organs of the body it is supposed to protect. Several autoimmune disorders can cause skin darkening. Thus if you have dark knuckles it is advisable to consult your healthcare provider at the earliest possible.
6. Addison’s Disease
Darkening of skin, especially at the joints like knuckles, can be one of the first symptoms of Addison’s disease. This may be accompanied by severe weakness, weight loss, etc.
This disease may be caused by the autoimmune attack on the adrenal glands, which produce the hormones cortisol and aldosterone. These two hormones help cope with stress and maintain the sodium-potassium balance in our body.
Thus, even though this disease is not so common, it can be life threatening. Hormone replacement therapies can help relieve the symptoms.
This is an inflammatory disease which affects the muscle and the skin. The most common symptoms include red or violet rashes around the eyelids, in the joints of arms like the elbows and knuckles. Pain in the joints and muscle weakness may be present too.
Dermatomyositis may be caused due to genetic, immunity or environmental factors. It can affect people of any age group. Treatment is focused on the individual’s symptoms. Topical application of corticosteroids may help alleviate the dark skin rashes.
8. Scleroderma And Raynaud’s Disease
Scleroderma is a rare autoimmune disorder affecting the skin and other connective tissues of the body. It is more common in women than men.
The symptoms of localized scleroderma are most evident on the skin, and thick, tight and discoloured patches around the arms and legs can be seen. Besides skin, muscles and joints, systemic scleroderma can affect vital organs like lungs, kidneys and heart.
Scleroderma is often associated with Raynaud’s phenomenon, in which fingers and toes change colour upon exposure to cold or stress. This happens due to the constriction of the blood vessels in the fingers or toes during an attack. The normal blood flow is usually restored after the episode is over.
9. Drug Reaction
One can develop dark knuckles as a side effect of using certain medications. Few medications that may cause darkening of the knuckles are:
- Protease inhibitors
- Nicotine acid
- Contraceptive pills
- Estrogen therapy
- Growth hormone therapy
- Injected insulin
- Certain antibiotics and antiviral drugs
- Nonsteroidal anti-inflammatory drugs
Darkening of knuckles due to drugs usually stops when the treatment is over. But you may consult your doctor for alternate medications if it worries you.
How To Lighten Dark Knuckles?
Common knowledge may suggest scrubbing or bleaching as a direct solution to lighten dark knuckles. But these approaches may be contraindicative, as excessive scrubbing can remove the outer protective epidermal layer and result in increased hyperpigmentation. Also, most store-bought bleaching products contain strong acids that only makes the darkening worse.
Here are some of the more effective options to treat dark knuckles.
1. Treatment Of The Underlying Causes
It is of utmost importance to identify and address the underlying causes of your dark knuckles. So, consult a doctor at the earliest possible. Often the dark knuckles will disappear when the conditions causing them have been treated correctly.
For example, attaining appropriate body weight and controlling blood sugar levels, will help control conditions like diabetes and PCOS. This, in turn, will help remove the hyperpigmentation of knuckles.
Taking dietary supplements for correcting vitamin B12 deficiency, or hormone replacement therapies might be required for correcting disorders like Addison’s disease or immunosuppressants for other autoimmune disorders.
2. Home Remedies
Keep your knuckles moisturised and apply sunscreen regularly to prevent further darkening. Some of these simple home remedies can also help you lighten knuckle hyperpigmentation.
A. Green tea
The ECGC (epigallocatechin-3-gallate) and vitamin E in green tea helps to lighten dark skin. You can steep green tea in warm water and use the concoction directly on your dark knuckles. Alternatively, you can apply a mixture of green tea leaves with milk and rose water to help lighten the skin of your knuckles.
Turmeric has curcumin, which is known for its skin lightening effect. Apply a paste of powdered turmeric in water on your knuckles, leave it for a few minutes and wash off.
C. Baking Soda
Make a paste of baking soda in water, apply it on your knuckles for 2 minutes in circular motion. Wash off and apply a moisturiser.
The high content of lactic acid in curd can effectively lighten dark skin. Apply curd on your knuckles and leave for 20 minutes before washing it off with warm water.
This rich source of vitamin E helps in skin lightening. Make a paste of almond powder in rose water and apply it on knuckles regularly to see the effects faster. Massaging almond oil on your skin can also help.
3. Over The Counter Remedies
If you are looking for faster results, then some of the over the counter (OTC) remedies can help. However, use these only after consultation with a dermatologist. Also, be aware that lightening the skin of your knuckles can take time and OTC products may work differently on different people.
Some OTC products for lightening dark knuckles are:
- Creams containing Kojic acid or Soy
- Serums with Niacinamide
- Moisturisers with Ellagic acid
- Products containing Hydroquinone
- Whitening cream with Lignin peroxidase
- Products containing Retinoids
When To See A Doctor?
Dark knuckles can often be the foreteller of a health condition, before other more serious symptoms have set in. So, if you have persistent dark knuckles that do not seem to improve with home remedies, it is better to consult a doctor.
Also, if you wish to opt for a cosmetic treatment such as laser therapy, consult a dermatologist, who can decide if it is the right choice of treatment for you.
Darkening of knuckles due to regular wear and tear of your skin should not be of much concern. It can easily be taken care of by routine cleansing, moisturising and application of sunscreen with a product that suits your skin type. However, dark knuckles can also indicate the presence of a health issue which might need immediate medical attention.
Appropriate treatment of the underlying health conditions usually helps reverse the darkening of knuckles. The choice of home remedies and OTC products are available to help lighten knuckle hyperpigmentation.
10. https://www.scleroderma.org/site/SPageNavigator/patients_whatis.html#.X7P53cj7 Q2w
11. https://www.rheumatology.org/I-Am-A/Patient-Caregiver/Diseases- Conditions/Scleroderma
12. https://www.rheumatology.org/I-Am-A/Patient- Caregiver/Diseases-Conditions/Raynauds-Phenomenon
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