What is a mole?

What causes moles?

No one quite knows why we get moles. Babies are usually born without any but then develop them over the first few months of life. You can go on developing new moles well into adulthood.

We do know that moles run in families, so if your mum and dad have them, then the chances are you will too. We also know that moles are affected by hormones, so they may change as you pass through puberty, pregnancy or the menopause.

Fair skinned people are more likely to get moles, as are those who spend a lot of time in the sun, especially during childhood.

Types of mole

Dermatologists use the term melanocytic naevi to describe moles. Most moles are round or oval, flat and brown in colour. But when you look closely, there are differences in size, shape and colour.

The most common moles are:

  • Junctional moles – round flat and brown
  • Dermal moles – pale, raised moles, often with hair
  • Compound moles – light brown, raised and hairy

Less common moles include:

  • Halo moles – a mole surrounded by a colourless ring
  • Dysplastic (atypical) moles – larger, less regularly shaped moles
  • Blue moles – dark blue in colour

Are moles dangerous?

Most moles are completely harmless and will not cause any problems. Sometimes, moles in obvious places, such as on the face and neck, can cause problems with self-image, especially in teenagers who may become self-conscious about how their moles make them look.

Raised moles can also be a problem if they catch on clothing or rub during your daily routine or when playing sports. Raised moles on the jaw line in men can also cause issues with shaving, as they will often get caught by the razor and bleed.

While most moles, even the nuisance ones, can be ignored without risking your health, some moles can develop into an aggressive form of skin cancer called melanoma. Malignant melanoma is much less common than other skin cancers but is the most serious, and importantly its numbers are increasing.

The good news is that melanomas can usually be treated successfully with no impact on your lifespan if they are diagnosed and treated early enough. This is why it’s important to keep an eye on your moles to spot worrying signs early.

Things to look out for

  • A mole changes its appearance.
  • A new different mole.
  • A new, solitary, different skin lesion.
  • It grows over a few weeks, becoming larger than 6 mm in diameter.
  • It grows and becomes much more domed than previously, even if its diameter does not increase.
  • It loses its regular smooth border and starts to look smudged, as if someone has tried to rub it out.
  • It changes colour, or becomes two-coloured.
  • Itching and bleeding are also warning signs but this can happen if a mole constantly catches on clothing.
  • Inflammation or reddening around the mole.



“You should check your skin for new moles, or changes to existing moles, every month, and if you have any concerns, seek medical advice. All of the above signs need to be checked out, but they do not always mean that a mole has become cancerous. Melanoma can occur on any skin site, and tends to be solitary and looks different from the remaining skin lesions. Remember – odd one out, check it out!”


Dr Jonathan Bowling runs a comprehensive mole screening service that provides total body dermoscopy, mole mapping and digital dermoscopy to screen moles and diagnose any problems.