Ketiak Hitam (Acanthosis Nigricans): Punca & Cara Hilangkan

Ketiak hitam with dark, thick, velvety skin is often a condition called acanthosis nigricans. It usually appears in the armpits, the back of the neck or the groin. It is not contagious and is usually harmless, but it can be an early sign of insulin resistance, prediabetes, type 2 diabetes or a hormone condition such as PCOS. The most common cause is excess weight, and the patches usually fade once the cause is treated. Scrubbing and whitening creams rarely help. This guide explains the signs, causes, link with kencing manis, treatment and when to see a doctor.

Apa itu ketiak hitam (acanthosis nigricans)?

The NHS describes acanthosis nigricans as dry, dark patches of skin that usually appear in the armpits, neck or groin. The American Academy of Dermatology (AAD) explains that it causes areas of skin to darken and thicken, and that the skin often feels like velvet.

Key points from the AAD:

• it is not contagious and it is not harmful in itself;
• people sometimes think the dark colour is a dye or something they touched, and try to scrub it away, but vigorous scrubbing will not get rid of it;
• sometimes it is a warning sign of a health problem that needs medical attention, which is why it is worth getting a new dark, thick patch checked.

Not every dark underarm is acanthosis nigricans. Darker skin in the armpit can also follow irritation or friction, or come from a skin infection (see other causes below). The thickened, velvety texture is what sets acanthosis nigricans apart.

Tanda acanthosis nigricans and where it appears

According to the NHS and AAD, the skin affected by acanthosis nigricans:

• is darker (brown or black) and thicker than the surrounding skin;
• feels dry and velvety;
• may have small skin tags on the patches;
• may be itchy, or have a bad smell (AAD).

Where it appears: the AAD says patches can form on most areas of the body. The NHS says they are most common in skin folds, such as:

• the armpits (ketiak);
• the neck, especially the back of the neck (sometimes called leher hitam);
• the groin.

The AAD says it can also appear on the elbows, knees, knuckles, belly button, under the breasts, on the face and around the genitals. Less often, it affects the lips, mouth, palms or soles of the feet.

How fast it appears: the NHS says the patches often appear gradually, without any other symptoms, and the AAD says it usually takes months or years to form. Patches that appear suddenly need a prompt check with a doctor (see when to see a doctor).

Punca ketiak hitam (causes)

The NHS says the most common cause is obesity. Other causes include:

• type 2 diabetes (see our guide to kencing manis);
• conditions that affect hormone levels, such as polycystic ovary syndrome (PCOS, now called PMOS), an underactive thyroid or Cushing's syndrome. Our guides to PCOS symptoms and tiroid explain the first two;
• certain medicines, including steroids and hormone treatments such as the contraceptive pill. The AAD also lists niacin;
• rarely, cancer, usually stomach cancer;
• rarely, a faulty gene inherited from your parents.

Healthy people can get it too. The NHS says some people with no other conditions get acanthosis nigricans, and that this is more common in people with brown or black skin. The AAD says these people tend to have others in their family with it. DermNet notes that in people with darker skin, acanthosis nigricans may appear without insulin resistance, so the skin sign alone cannot tell you whether you have a blood sugar problem. A check-up can.

Ketiak hitam, insulin resistance & kencing manis

Why it happens: DermNet explains that acanthosis nigricans is mostly linked to insulin resistance. This is when the body does not respond well to insulin, so it needs more insulin to keep blood sugar normal. DermNet says high insulin levels can stimulate skin cells to multiply, which leads to the thick, dark patches.

A sign worth acting on:

• the AAD says acanthosis nigricans can be a sign of prediabetes, and that making lifestyle changes before diabetes develops can prevent diabetes;
• DermNet describes it as an independent risk factor for diabetes. It cites a US study of 1,730 people in which those with acanthosis nigricans were about twice as likely to have type 2 diabetes (35.4% compared with 17.6%);
• the American Diabetes Association (ADA) Standards of Care 2026 list acanthosis nigricans among the conditions linked to insulin resistance that should prompt diabetes or prediabetes testing in adults with overweight or obesity. For people of Asian ancestry, this means a BMI of 23 or more.

The same ADA list includes PCOS and fatty liver disease. See our guides to PCOS and hati berlemak (fatty liver).

Why this matters in Malaysia: the National Health and Morbidity Survey (NHMS) 2023 found that 15.6% of the population surveyed had diabetes, and younger people were more likely to have undiagnosed diabetes. If you notice ketiak hitam or leher hitam, asking a doctor for a blood sugar test is a simple next step.

Other causes of dark underarms

Darker armpits are common, and not all of them are acanthosis nigricans. DermNet lists several skin conditions that can look similar:

If you are not sure what is causing your dark armpits, a doctor can usually tell by looking at the skin.

How doctors check ketiak hitam

The NHS and AAD say a doctor can usually tell if it is acanthosis nigricans by looking at your skin. Because it can be a sign of another condition, you may then need tests to find the cause. These may include:

• a blood sugar test or other testing for diabetes (MedlinePlus);
• other blood tests and medical tests, for example to look for thyroid or other hormone problems, depending on your symptoms (AAD);
• rarely, a skin biopsy if the diagnosis is unclear, or tests such as an endoscopy or X-rays if there is no clear cause (MedlinePlus).

Tell your doctor about all the medicines you take, including the contraceptive pill and any steroids, as some medicines can cause the patches (AAD).

Cara hilangkan ketiak hitam (treatment)

1. Treat the cause first. The NHS says the patches should fade over time once the cause is treated. Depending on the cause, this may mean:

• losing weight if you are very overweight. The AAD says studies show that when people with obesity and acanthosis nigricans lose a significant amount of weight, their skin often clears. Our guide to losing weight safely in Malaysia has practical steps;
• managing prediabetes or diabetes. The AAD says getting prediabetes under control often helps the patches fade. DermNet says healthy eating and more exercise aim to improve insulin resistance, and that metformin, a diabetes medicine that reduces insulin levels, can moderately improve the skin. Your doctor will decide whether you need it;
• treating a hormone condition, such as PCOS or a thyroid problem (NHS, AAD);
• changing a medicine that causes the patches, if your doctor agrees (NHS).

The AAD notes that treating the cause does not always clear the patches completely, and that some people have acanthosis nigricans without any medical condition.

2. Treatments for the skin itself. The NHS says there is no specific treatment for the patches, but a skin specialist (dermatologist) may suggest treatments to improve their appearance. The AAD says treatment is not necessary, but if you want clearer skin, a dermatologist may use:

The AAD says none of these treatments is designed specifically for acanthosis nigricans, and that it can sometimes be difficult to treat. MedlinePlus says acanthosis nigricans often disappears if the cause can be found and treated.

What not to do

• Do not scrub hard. The AAD says vigorous scrubbing will not get rid of acanthosis nigricans.
• Ask a doctor before using bleaching or whitening creams and exfoliants. The AAD says these products rarely fade acanthosis nigricans and can irritate the skin, making it worse.
• Avoid unregistered whitening products. A study of 104 whitening products on the Malaysian market found that 16 contained mercury above the 1 ppm limit, even though none listed mercury as an ingredient, and 14 of these 16 were not registered with the National Pharmaceutical Regulatory Agency (NPRA). Our guide to krim merkuri explains the warning signs and how to check a product's status.
• Do not ignore new patches. The AAD says a small change can be an early warning sign, and that lifestyle changes made before diabetes develops can prevent it.

Dark neck in children: a note for parents

Acanthosis nigricans can also appear in children, especially those who are overweight. The AAD says obesity is the most common cause in both adults and children.

• In a Malaysian school programme (MyBFF@school) involving 924 schoolchildren with overweight or obesity (average age about 10), acanthosis nigricans was found in 83.7% of the children with severe obesity.
• The ADA Standards of Care 2026 list acanthosis nigricans as a sign of insulin resistance that should prompt diabetes screening in children and teenagers with overweight or obesity, after puberty starts or from age 10, whichever comes first.

If your child has a dark, velvety neck or armpits that do not wash off, do not scrub it. Speak to a doctor at a klinik kesihatan or your GP, who can check your child's weight and blood sugar.

When to see a doctor

The NHS advises seeing a GP if:

• you have new dark patches on your skin;
• you have any skin changes you are unsure about.

See a doctor promptly if many dark, velvety patches appear suddenly or spread quickly. The AAD and MedlinePlus say that acanthosis nigricans that develops rapidly can be a sign of cancer, although this is rare. DermNet notes it is more likely in middle-aged people who are not overweight.

Also see a doctor if you have dark patches together with symptoms of diabetes, such as feeling very thirsty, or with irregular periods, acne or excess hair, which can point to PCOS. In Malaysia, you can start at a klinik kesihatan or a GP, who can arrange blood tests and refer you to a dermatologist or other specialist if needed.

Frequently asked questions (FAQ)

Apa itu ketiak hitam (acanthosis nigricans)?

Acanthosis nigricans is the medical name for patches of skin that are darker and thicker than usual and feel velvety. It usually appears in the armpits (ketiak), the back of the neck or the groin. It is not contagious and is usually harmless, but it can be a sign of an underlying condition such as insulin resistance, prediabetes or type 2 diabetes, so it is worth getting checked by a doctor.

Apa punca ketiak hitam (what causes dark armpits)?

The NHS says the most common cause of acanthosis nigricans is obesity. Other causes include type 2 diabetes, hormone conditions such as PCOS (now called PMOS), an underactive thyroid or Cushing's syndrome, and some medicines, such as steroids or the contraceptive pill. Rarely, it is caused by cancer or an inherited gene. Some healthy people get it too, and it is more common in people with brown or black skin.

Adakah ketiak hitam tanda kencing manis (is a dark armpit a sign of diabetes)?

It can be. The American Academy of Dermatology says acanthosis nigricans can be a sign of prediabetes or diabetes, and the American Diabetes Association lists it as a condition linked to insulin resistance when deciding who should be screened for diabetes. Not everyone with dark armpits has diabetes, so a simple blood sugar test is the best way to find out.

Bagaimana cara hilangkan ketiak hitam (how to get rid of dark armpits)?

The main step is to find and treat the cause. The NHS says the patches should fade over time once the cause is treated, for example by losing weight if you are very overweight, treating diabetes or a hormone condition, or changing a medicine that causes the patches. A dermatologist can suggest treatments to improve the appearance, such as prescription creams, retinoids or laser, but these may not clear it completely.

Can whitening cream or scrubbing remove ketiak hitam?

Not reliably. The American Academy of Dermatology says vigorous scrubbing will not get rid of acanthosis nigricans, and that bleaching creams and exfoliants rarely fade it and can irritate the skin, making it worse. Ask a doctor before using one, and avoid unregistered whitening creams, as some sold in Malaysia have been found to contain mercury.

Is acanthosis nigricans dangerous?

The patches themselves are not harmful or contagious. What matters is the cause, as they can be an early sign of prediabetes, diabetes or a hormone problem. Rarely, dark patches that appear suddenly and spread quickly can be a sign of cancer, usually in the stomach, so see a doctor promptly if this happens.

Is ketiak hitam linked to PCOS?

Yes. The NHS and the American Academy of Dermatology list PCOS (polycystic ovary syndrome, now called PMOS) as one of the hormone conditions that can cause acanthosis nigricans, because PCOS is closely linked to insulin resistance. If you have dark velvety patches together with irregular periods, acne or excess hair, see a doctor about PCOS.

Disclaimer

This article is for general information only and is not a substitute for advice, diagnosis or treatment from a doctor. Health supplements are not intended to diagnose, treat, cure or prevent any disease.

References

• Acanthosis nigricans — NHS
• Acanthosis nigricans: Overview — American Academy of Dermatology (AAD)
• Acanthosis nigricans: Signs and symptoms — AAD
• Acanthosis nigricans: Who gets and causes — AAD
• Acanthosis nigricans: Diagnosis and treatment — AAD
• Acanthosis nigricans: Tips for managing — AAD
• Acanthosis nigricans — DermNet
• Acanthosis nigricans — MedlinePlus, US National Library of Medicine
• American Diabetes Association. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1):S27–S49.
• Nur Zati Iwani AK, et al. Cardiometabolic risk factors among children who are affected by overweight, obesity and severe obesity. Front Public Health. 2023;11:1097675.
• Conducting the National Health and Morbidity Survey 2023 in Malaysia with focus on methodology and main findings on non-communicable diseases — Scientific Reports
• Wan Mohamed Radzi CWJ, Nordin FNM. Status of cosmetic safety in Malaysia market: mercury contamination in selected skin whitening products. J Cosmet Dermatol. 2022;21(12):6875–6882.