New Mole: Possible Causes and When to Worry

Medically Reviewed By Debra Sullivan, Ph.D., MSN, R.N., CNE, COI
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A new mole does not always signify skin cancer. New moles can also appear due to genetic factors, hormone changes, and sun damage.  Your skin is your body’s largest organ, and it changes throughout your lifetime. New moles, or nevi, can be one of these changes, and seeing them appear may cause concern.

A new mole is not always a sign of skin cancer, such as melanoma. However, if the mole quickly changes in size, shape, and color, it may indicate something more serious.

Always consult your doctor about any mole that changes or looks different from other ones on your body.

Keep reading to learn about whether new moles are common, what may cause a new mole, and melanoma warning signs to look for.

Are new moles common?

Woman standing with bare back with unseen person's hand checking for moles
Oleksandra Stets/Stocksy United

It is not unusual for adults up to the age of 40 to develop a new mole, according to the National Library of Medicine.

Moles in general are very common. Most people have between 10 and 40 moles. In most cases, they develop them as children or teenagers.

Your moles may change appearance throughout your lifetime. For example, they may fade or get darker. 

The risk of melanoma increases after age 40. Therefore, it is particularly important for older adults to monitor any new moles that appear. Keep track of them and document their appearance. Consider taking monthly photos of any new moles.

If you notice any sudden changes or growth of either a new or existing mole, contact a doctor for evaluation. 

Learn eight things doctors want you to know about moles.

What causes new moles?

While doctors are unsure exactly what causes new moles, there are a few risk factors associated with their development.

New moles appear for a variety of reasons, including: 

  • Genetics: Researchers note comparable amounts of moles in multiple generations of families. While moles seem to be an inherited trait, researchers are unsure of the inheritance pattern. 
  • Hormone changes: New moles can appear during times when your body is undergoing hormonal changes, like during puberty or pregnancy
  • Sun exposure: New moles seem to appear after prolonged sun exposure. New moles are different from freckles, however. Moles contain extra pigment-forming cells and more blood vessels. They are also raised, while freckles are flat. 
  • Treatments that affect immunity: Some medications that suppress the immune system can cause an increase in moles.
  • Melanoma: Skin cancer can also cause new moles to appear. Melanoma is a type of skin cancer. It occurs when the cells that produce brown or tan pigments grow rapidly and out of control. 

Some causes of new moles cannot be changed, like genetics and hormone changes. However, you can take preventive steps for the factors you can control.

Wearing sunscreen and protective sun gear lowers your risk of moles or melanoma due to sun damage. Make sure to protect frequently overlooked areas, like your hairline and ears. 

Keep in mind that freckles and sunspots differ from moles. Sunspots and freckles are flat, whereas moles are slightly raised. 

Learn 10 ways to protect your skin from the sun.

What are symptoms of melanoma?

A new mole that looks different than other moles on your body could be a warning sign of melanoma. A mole that is changing in appearance can also be a warning sign.

When a new mole could be melanoma

The American Cancer Society recommends using the acronym ABCDE to look for possible cancerous moles: 

  • A for asymmetry: One half of the mole is a different shape than the other. 
  • B for border: The edges of the mole are not smooth and defined but irregularly shaped or blurred. 
  • C for color: The mole does not have a uniform color throughout. You may see patches of white, pink, or even blue. 
  • D for diameter: The spot is larger than 6 millimeters (mm) in diameter. 
  • E for evolving: The mole is changing rapidly in shape or size. 

Learn more about the ABCDEs of melanoma.

Other warning signs of melanoma include moles that:

  • feel tender to the touch
  • have broken, oozing skin that does not heal
  • bleed without scratching

In its later stages, metastatic melanoma can cause symptoms including:

Contact a dermatologist or other doctor right away for any suspicious moles or signs of melanoma. Early detection is essential for successful melanoma treatment.

What are types of moles?

There are a variety of noncancerous moles that you may develop. These types fall into two primary categories.

Common mole 

Common moles often appear above the waistline in areas that receive sun exposure. These moles are smaller than 5 mm wide, which is about the size of a pencil eraser.

Common moles are circular or oval-shaped. They have a slightly raised appearance. Common moles vary in color from light pink to brown. These types of moles rarely turn into melanoma

Atypical mole

An atypical mole, also known as a dysplastic nevus, is a mole that differs in appearance from a common mole. For example, it may be larger than a common mole and have jagged edges.

An atypical mole may also be similar in color to a common mole. However, they feature patches of other colors as well, like blue or pink. About 1 in 10 people have at least one atypical mole. Atypical moles are more likely to develop into skin cancer

Learn more about how to identify atypical moles.

Normal moles vs. suspicious moles

Doctors do not consider common moles to be dangerous. However, they identify atypical moles as suspicious moles.

While suspicious moles indicate a potential increased risk for melanoma, they do not require removal unless they start changing in appearance

When should you see a doctor for a new mole?

Schedule a skin exam if you have a new mole that:

  • is atypical
  • differs from other moles on your body, known as an “ugly duckling
  • changes in appearance
  • develops symptoms such as oozing or bleeding without scratching

If you have more than five atypical moles, your doctor may recommend routine skin exams every 1–2 years.

If you have a family history of melanoma, you may need to have an exam more frequently, such as every 3–6 months. 

Summary

New moles are common in adults under 40, especially on areas with frequent sun exposure.

New moles can appear as common or atypical moles. Common moles are consistent in color, symmetrical, and have smooth borders. Atypical moles have jagged or blurred edges and may contain patches of different colors. Atypical moles are also larger than the size of a pencil eraser.

Very few common moles develop into melanoma. Doctors typically only remove new atypical moles if they start changing in appearance. 

Contact a dermatologist or other doctor right away for any suspicious moles or melanoma symptoms, as early detection is vital for successful treatment.

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Medical Reviewer: Debra Sullivan, Ph.D., MSN, R.N., CNE, COI
Last Review Date: 2022 Nov 17
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