What Causes Sun Spots on Skin?

what causes sun spots on skin

Are you wondering what causes the sun spots on your skin? Are you seeing more brown spots on parts of your skin exposed to sun such as the back of your hands, sides of your face and neck, your arms and top of your shoulders, even the V of your chest where your shirt exposes skin to sun? Sunspots are common, they also tell you where you need better sun protection.

Sun Spots on skin, called solar lentigines, are due to sun exposure.

They are flat, brown spots that show up on the parts of your skin that have been exposed to the sun. Once you start getting sun spots on your skin, expect them to darken and increase in number with every UV ray that hits your skin.

Any UV ray from the sun will darken your sun spots. Yes, that means that even the sun that comes through windows, that bounces off cement or water or that passes through clouds will worsen your sun spots.

What about tanning beds, will tanning beds give you sun spots?

Can you outwit the process and avoid sun spots by tanning in a tanning bed with unnatural UV light instead of in the sun with natural UV light?

No, tanning-bed UV rays will cause sun spots on skin, too. In fact, tanning-bed "freckles" as they are called, are often more numerous on the skin than the sunspot sun freckles from natural UV light. In my opinion, they also have a really unnatural look. This means that when I do a skin exam, I can usually tell if my patient has had tanning-bed exposure. Think of the cause and effect this way:

UV Ray exposure + Your Skin = Sun Spots!

How common are sunspots?

Almost everyone will eventually get sun spots on their skin from sun exposure. Some people start getting them earlier in life. These are usually people with really fair skin. If your skin is prone to developing sun spots, they can start showing up as early as your 20s, though most people start really noticing them in their 30s and 40s.

Discover sun spots on skin or solar lentigines Solar lentigines, aka suns pots, on the side of the face

What are the first parts of your skin that get sun spots?

Your first sun spots often show up on the sides of your face, the sides of your neck, the 'V' of your chest, and the back of your hands. 

These are the areas of your skin that get the most lifetime sun exposure. If you are a man whose scalp hair is thinning, sun spots will start dotting the top of your scalp, too.

Eventually, all of the parts of your skin that are exposed to the sun will develop sun spots. The shaded areas have fewer or none.

To see the way sun causes sun spots, find someone with sun spots on their arms. Look at the outer side of the arm and compare it to the underside. There are usually many more sun spots, both small and large, on the outer side of the arm than on the sun-protected underside. I like to teach patients the importance of sun protection by demonstrating this phenomenon on their skin. - Dermatologist Dr. Cynthia Bailey

Remember that sun protecting your skin helps prevent sun spots as well as skin cancer, wrinkles, crepey skin etc. Use shade (such as a real sun hat) and broad spectrum SPF 30+ sunscreen on all exposed skin every day. I recommend zinc oxide based sunscreens as I've found them to be the most reliable - demonstrated in over 200,000 skin exams during my career. Click here for the sunscreens I trust and sun protection tools that I know work. 

Dermatologist's sunscreen and hat to prevent sunspots

Are sun spots dangerous or precancerous?

True sun spots on skin are harmless. They don’t turn into skin cancer. BUT skin cancer can mimic a sunspot. All of the common skin cancer types can start as a flat brown patch. Because sun spots often have irregular boarders and variable shades of brown, it may be hard to tell by looking if a brown spot is worrisome for skin cancer.  

Said another way, sun spots on skin can mimic cancer and demonstrate the ABCDE signs of melanoma, meaning that you may need a skin exam by a dermatologist in order to tell the difference.

Also, the presence of a lot of sun spots indicates that you have had more sun exposure than your skin can handle, which means that you are at increased risk for skin cancer in the areas with the spots.

It’s safest to have an annual skin exam done by a dermatologist if your skin has a number of sun spots. In addition, your skin will have a unique "style" or pattern to its sun spots. And, your dermatologist can teach you how to better tell the difference between your sun spots, other age spots and skin cancer. Once you know this information, you can then do your own monthly skin exams with more confidence.

What exactly are sun spots on the skin?

  • Sun spots on skin are a focal increase of skin pigment called melanin; because of UV exposure, the pigment-making cells, called melanocytes, produced excess pigment in just one spot instead of uniformly across your skin surface.
  • The important point is that there is no increase in the number of the melanocyte cells, just in the pigment that they produced.

Moles and melanoma, on the other hand, have an increase in number of the actual melanocyte cells. In the case of moles, these melanocytes are not cancerous. In the case of melanoma, the melanocytes are cancerous. The cancerous cells of melanoma can spread all over the body and kill.

When you are looking at brown spots on your skin, it is not always easy to tell the difference between a sun spot, a mole and a melanoma with the human eye. This is why doctors sometimes have to perform biopsies of brown skin spots to make an exact diagnosis.

A biopsy is a procedure where either the entire brown spot or part of it is cut out and examined with a microscope. It allows the doctor to clearly see what’s going on under the skin to determine if the brown spot is made up of only skin pigment or if there is also an increase in the pigment producing cells called melanocytes.

Assuming that all the unwanted brown spots on your skin are just simple sun spots, how can you get rid of them?

I’ll talk about that in the next post.

Prevent sun spots like a dermatologist! 

best sunscreen to prevent sun spots
Click here to see my broad spectrum invisible zinc oxide sunscreens created with a patented zinc oxide formulation. 


Don't miss the other 3 posts in this dermatology series on sun spots - cause and cure:

Post 1. What Causes Sun Spots on Skin? (this post)

Post 2. How to Get Rid of (Prevent) Skin Sun Spots

Post 3. What Are the Best Skin Care Products to Fade Sun Spots 

Post 4. How to Get Rid of Those Pesky Sun Spots (With Procedures!)

Want to read more?

Click here to learn more on how to get rid of sun spots!