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Acanthosis nigricans

Acanthosis nigricans is the name for dry, dark patches of skin that usually appear in the armpits, neck or groin. It could be a sign of an underlying condition, so it needs to be checked by a GP.

Check if you have acanthosis nigricans

The main symptom of acanthosis nigricans is patches of skin that are darker and thicker than usual.

They can appear anywhere on the body.

Dark patches of skin that form a band around the lower part of the neck on a person with medium brown skin.
The patches are dry and feel similar to velvet.
A dark patch of skin on the armpit of a person with white skin. The patch covers most of the person's armpit.
They're most common in skin folds, such as the armpits, neck or groin.
Dark patches of skin covering the armpit of someone with medium brown skin. There are also about 50 small skin tags.
Some people also have tiny growths (skin tags) on the patches.

The patches often appear gradually without any other symptoms.

Sometimes the skin may be itchy.

Non-urgent advice: See a GP if you have:

  • new dark patches on your skin
  • any skin changes you're unsure about
Information:

Coronavirus (COVID-19) update: how to contact a GP

It's still important to get help from a GP if you need it. To contact your GP surgery:

  • visit their website
  • use the NHS App
  • call them

Find out about using the NHS during COVID-19

What happens at your appointment

Although acanthosis nigricans is usually harmless, it's best to get any skin changes checked out.

Rarely, it can be a sign of something more serious, such as cancer.

A GP can usually tell if it's acanthosis nigricans by looking at your skin.

You may need some tests to find out what's causing the patches.

Causes of acanthosis nigricans

The most common cause of acanthosis nigricans is being very overweight.

Other causes include:

Sometimes healthy people with no other conditions get acanthosis nigricans. This is more common in people with black or brown skin.

Treating acanthosis nigricans

Once a GP knows what's causing acanthosis nigricans, they can recommend the best treatment.

The patches should fade over time once the cause is treated.

If you're very overweight, a GP may recommend losing weight.

Depending on the cause, they may also recommend:

  • medicine to balance your hormones
  • medicine to balance your insulin levels
  • changing your medicine to one that does not cause the patches

There's no specific treatment for the patches themselves. A skin specialist (dermatologist) may be able to suggest treatments to improve their appearance, but finding and treating the cause is usually recommended first.

Page last reviewed: 20 June 2021
Next review due: 20 June 2024