Quick answer

What could mole changes mean?

Most moles are harmless, but a changing mole can be a sign of melanoma — the most serious type of skin cancer. See a GP urgently for a mole that changes shape, colour, size or bleeds, or looks different from your other moles. The ABCDE guide helps identify concerning features. Melanoma is highly treatable when caught early.

Why a changing mole matters

Most moles (naevi) are harmless collections of pigment cells, and many people have dozens of them. However, melanoma — the most dangerous form of skin cancer — often starts as a new mole or a change in an existing one. Melanoma is highly curable when caught early, which is why knowing the warning signs and seeing a GP promptly matters.

The UK diagnoses about 16,000 melanomas a year, and rates are rising — partly due to sun exposure and better detection.

The ABCDE guide for checking moles

Use the ABCDE guide to identify moles that need assessment:

A — Asymmetry. One half of the mole looks different from the other. Benign moles are usually symmetrical.

B — Border. The edges are irregular, blurred or jagged rather than smooth and clearly outlined.

C — Colour. The colour is uneven, with multiple shades — brown, black, tan, red, white or blue within one mole. Benign moles are usually one uniform colour.

D — Diameter. The mole is larger than 6mm (about the size of a pencil eraser) — though melanomas can be smaller than this, so do not ignore small suspicious moles.

E — Evolving. The mole is changing in size, shape, colour or elevation, or has developed new symptoms such as bleeding, itching or crusting.

Other warning signs of melanoma

See a GP if:

  • a new mole appears after the age of 30
  • a mole looks different from your others (the “ugly duckling” sign)
  • a mole bleeds without injury
  • one mole itches persistently
  • a dark streak appears under a fingernail or toenail (acral melanoma)
  • a sore does not heal within 4 weeks
  • a new skin lesion grows quickly

Who is at higher risk of melanoma

Your risk of melanoma is higher if:

  • you have fair skin that burns easily and tans poorly
  • you have a history of sunburn, especially blistering sunburn in childhood
  • you have many moles — more than 100
  • you have atypical moles, meaning large or irregular moles
  • you have a family history of melanoma
  • you have used sunbeds, which significantly increase melanoma risk
  • you have a weakened immune system, for example as an organ transplant recipient or through immunosuppression

Melanoma can occur on any skin type, including dark skin — though it is less common. In darker skin tones it may appear on the palms, the soles, and under the nails.

How to check your skin for mole changes

  • Examine your skin monthly, including your back (use a mirror or ask a partner), scalp, between your toes, the soles of your feet, and the genital area.
  • Photograph existing moles so you can track any change over time.
  • Report any new or changing lesion promptly — do not watch and wait for months.

What a GP will do about a changing mole

A GP examines the mole, often with a dermatoscope (a magnified light). They may:

  • reassure you if the mole is clearly benign
  • refer you to dermatology on an urgent suspected cancer pathway if they are concerned
  • photograph and monitor the mole if they are uncertain but suspicion is low

Suspicious moles are removed by excision biopsy — cut out with a margin of normal skin — and examined under a microscope.

How melanoma is treated

Treatment depends on the thickness (Breslow depth) of the melanoma and whether it has spread. For thin melanoma, excision alone is usually curative. Thicker melanoma may need wider excision, sentinel lymph node biopsy, immunotherapy, or targeted therapy.

Early melanoma (stage 1) has over 95% five-year survival. Delayed diagnosis worsens the prognosis.

Other types of skin cancer

Not all skin cancer is melanoma. Basal cell carcinoma (BCC) is the most common type; it appears as a pearly nodule that may ulcerate, grows slowly and rarely spreads. Squamous cell carcinoma (SCC) appears as a scaly or crusted growth and can spread if left untreated.

Both need treatment but are less aggressive than melanoma. Any persistent, non-healing skin lesion needs GP assessment.

Sun protection to reduce skin cancer risk

  • Apply SPF 30+ sunscreen generously and reapply every 2 hours.
  • Seek shade between 11am and 3pm in summer.
  • Cover up with a hat, sunglasses and long sleeves.
  • Never use sunbeds.
  • Protect children from the sun, because sunburn in childhood increases melanoma risk.

Sun protection reduces the risk of all types of skin cancer.

Why mole-checking apps are not enough

Mole-checking phone apps can help with awareness, but they do not replace GP assessment of concerning lesions. If you are worried, see a GP — dermatology referral is appropriate.

When to see a GP about a mole

Embarrassment or minimisation (“it’s probably nothing”) delays melanoma diagnosis. GPs would much rather reassure you about a benign mole than miss an early melanoma. The two-week wait referral exists for suspicious skin lesions — use it.

Common questions about mole changes

What is the ABCDE guide for moles?
The ABCDE guide lists five warning features — Asymmetry (the two halves look different), Border (irregular or blurred edges), Colour (uneven with multiple shades), Diameter (larger than 6mm, though melanomas can be smaller) and Evolving (changing in size, shape or colour). Any one of these features warrants assessment.
What does melanoma look like?
Melanoma usually appears as a new mole or a change in an existing mole, often brown or black but sometimes pink, red or skin-coloured. It may be flat or raised with an irregular shape and uneven colour, and it may bleed, itch or crust. It can appear anywhere on the body, including areas not exposed to the sun.
Are all changing moles cancer?
No, not all changing moles are cancer, as moles can change benignly with age. However, any change should be assessed because melanoma can mimic benign moles. A GP or dermatologist uses a dermatoscope to examine moles closely.
How can I reduce my skin cancer risk?
You can reduce your risk by avoiding sunburn — use SPF 30+ sunscreen, seek shade between 11am and 3pm, cover up and never use sunbeds. Check your skin regularly, including your back, scalp and the soles of your feet, and report new or changing lesions promptly.
What happens if a mole is suspicious?
A GP or dermatologist examines the mole with a dermatoscope, and suspicious moles are removed surgically (an excision biopsy) and examined under a microscope. If melanoma is confirmed, further treatment depends on its thickness and stage — early melanoma is usually cured by excision alone.

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