Key Information

• Early Detection: Most moles are harmless, but spotting changes early is vital. Changing moles can be a sign of melanoma.
• The Memory Aid: Clinicians use a simple five-letter guide, ABCDE, to check moles.
• The Rule: If you see any of the signs below, or if a mole just "doesn't seem right," get it checked.

The ABCDE Guide

Use these five letters to check your moles with confidence:

A - Asymmetry

• Imagine drawing a line down the middle of the mole.
• Warning Sign: If the two halves look very different from each other.

B - Border

• A normal mole usually has a smooth, even border.
• Warning Sign: If the edge is irregular, scalloped, or poorly defined.

C - Colour

• Most harmless moles are just one single shade of brown.
• Warning Sign: If the mole has multiple, blotchy colours (different shades of brown, black, tan, or even red, white, or blue).

D - Diameter

• Warning Sign: If the mole is larger than 6mm (about the size of the rubber on the end of a pencil).
• Note: Melanomas can start smaller than this.

E - Evolving (The Most Important)

• This simply means "changing."
• Warning Sign: Any mole that changes in size, shape, colour, or texture over weeks or months. Also, look out for itching or bleeding.

If you remember only one letter, remember E.

Your Routine

We recommend that you get into the habit of checking your skin (including your back) about once a month.

What Happens Next?

If you find a mole with any of these ABCDE features, or you notice a new mark that is worrying you:

• Do not wait. Finding melanoma early makes it much easier to treat.
• Contact us. Use our online service to request a review.

Discuss Your Skin

Further Information

Sun Safety

Non-Melanoma Skin Cancer

For visual examples of melanoma and more information on risk factors, please visit the NHS website.

Learn more about melanoma

Last reviewed: 12 April 2026
Next review due: 12 April 2029