Melanoma Risk Factors, Causes & Prevention

Melanoma Risk Factors, Causes & Prevention


What is My Risk for Melanoma?

These are the risk factors for melanoma:

  • Sun exposure.
  • Age.
  • Atypical moles.
  • Many moles.
  • Large moles at birth.
  • Personal or family history of melanoma.
  • Fair skin.

Sun Exposure

Overexposure to ultraviolet (UV) radiation from the sun is the major risk factor for skin cancer, including melanoma. The radiation reaches you by invisible rays from the sun. The 2 kinds of UV radiation are UVB and UVA.

UVB radiation causes sunburns and blistering. Scientists think UVB causes most skin cancers. Melanoma most often starts in people who were exposed to UVB radiation, especially if they had sunburns or blistering. People who work outside, spend time at the beach, or do outdoor sports have a higher risk for skin cancer.

UVA radiation also causes skin damage. UVA rays can travel through glass and clouds. Exposure to UVA rays can lead to early aging and skin cancer, according to the National Cancer Institute. Sun lamps and tanning beds also cause exposure to harmful UVA rays. You should avoid them.

Melanoma also can start in parts of your body that are not exposed to sunlight. This includes the bottoms of your feet, hands, nails, and the membranes lining the eyes, sinuses, anus, and vagina. These are rare conditions that anybody can develop, and doctors are still trying to understand why they happen.


It usually takes a long time from when your skin was exposed to harmful UV rays and when melanoma starts. Most melanoma is in older people. As you age, it’s also harder for your body to fix damage from the sun. This raises your cancer risk. Children rarely get melanoma.

Atypical Moles

You’re at higher risk for melanoma if you have moles that are:

  • Unusually large.
  • Unevenly shaped.
  • Asymmetrical (they don’t look the same on all sides).
  • Many colors.
  • Flat and bumpy.

Sometimes these types of moles run in families.

Many Moles

You’re at higher risk for melanoma if you have many moles, even if they look normal.

Large or Giant Congenital Moles (Birth Marks)

Having unusually large moles at birth could lead to melanoma. Your risk for melanoma depends on the size of the mole. You’re at higher risk if you have bigger moles.

Personal or Family History of Melanoma

You’re at much higher risk of getting melanoma again if you already had the disease. You’re also at higher risk if your parents or siblings related to you by blood (blood relatives) had melanoma.

Some people inherit a genetic mutation (change) from their parents. They are born with genes that make it more likely they will get melanoma. One example is the CDKN2A mutation.

You may have a strong family history of melanoma. Learning you have a mutation can help you make choices that can lower your risk for melanoma. Your doctor may suggest you and your blood relatives get tested for mutations.

Fair Skin

You’re at higher risk of getting skin cancer, including melanoma, if you have any of these:

  • Fair skin.
  • Blue or light-colored eyes.
  • Blond or red hair.

People with fair skin have less melanin, a skin pigment. Melanin gives skin, hair, and eyes their color. It also gives some natural protection from the sun. However, people with dark skin, who have more melanin, can still get melanoma. Skin that freckles or sunburns easily can be a warning sign you’re at risk for melanoma.

Learn more about types of melanoma that can develop in people with dark or black skin.

Skin Cancer Prevention

The best way to protect yourself from skin cancer is to avoid ultraviolet (UV) light from the sun’s rays. We recommend you:

  • Wear protective clothing such as long-sleeve shirts, wide-brimmed hats, and sunglasses.
  • Protect yourself from sun rays by wearing broad-spectrum sunscreen. Broad spectrum means it blocks both types of UV rays (UVA and UVB). 
  • Apply sunscreen with an SPF of 30 or higher 30 minutes before going outside. Do this even on cloudy days and in the winter.
  • Apply a thick layer of sunscreen, about 2 tablespoons, on your face and body.
  • Reapply sunscreen every 2 hours and after swimming, toweling, or sweating.
  • Stay out of the sun from 10 a.m. to 4 p.m. when rays are the strongest.
  • Get into the shade whenever possible.
  • Do not use indoor tanning machines.

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