The short answer
UV radiation is invisible energy from the sun and from tanning beds. It can damage the DNA inside skin cells, and over time that damage can lead to skin cancer, including melanoma. UVA and UVB rays both cause harm, so limiting UV exposure is the key to lowering your risk.
UV radiation is the main preventable cause of skin cancer.
Both UVA and UVB rays damage skin; there is no safe amount of tanning UV.
UV damages the DNA inside skin cells, which can lead to cancer over time.
The sun and tanning beds are both sources of harmful UV.
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The full explanation.
The simple version
UV radiation is invisible energy that comes from the sun. Tanning beds and sun lamps give off UV too. You cannot see or feel UV the way you feel heat, but it reaches your skin and can cause harm.
When UV hits your skin, it can damage the tiny instruction code inside your skin cells, called DNA. Over time, this damage can build up and lead to skin cancer.
UV radiation is the single biggest preventable cause of skin cancer — and both the sun and tanning beds are sources of it.
What UV radiation is
The sun sends out many kinds of energy. Some of it is visible light. Some of it is UV, which stands for ultraviolet.
Scientists group the UV that reaches us into two main types:
- UVB rays mostly affect the outer layer of skin and are the main cause of sunburn.
- UVA rays reach deeper into the skin and add to long-term damage and skin aging.
Both types can harm skin cells and both play a role in skin cancer. That is why protection that covers both — called broad-spectrum — is recommended.
How UV damages skin cells
Inside every skin cell is DNA, the code that tells the cell how to work and when to grow. UV rays can break or scramble parts of this code.
Your body has repair systems that fix a lot of this damage. But when UV keeps coming — day after day, summer after summer — the damage can pile up faster than the cell can fix it.
When damaged cells begin to grow and divide without stopping, that is how cancer can start.
A tan is not a sign of health — it is a sign your skin is trying to protect itself from UV damage that has already happened.
Sunburn and tanning are warning signs
A sunburn is a clear sign that UV has injured your skin. Even after the redness and peeling are gone, the DNA damage inside the cells remains.
A tan is also a response to UV damage. When skin is exposed to UV, it makes more pigment to try to shield itself. So both burning and tanning mean UV has reached your skin.
Blistering sunburns, especially during childhood and teen years, are linked to a higher risk of melanoma later in life.
Tanning beds are a UV source too
It is a common myth that tanning beds are a safe way to get color. They are not.
Tanning beds and sun lamps give off UV radiation, and using them raises the risk of skin cancer, including melanoma. The risk is higher for people who start using them when they are young.
There is no safe tan from UV, whether it comes from the sun or a machine.
Why everyone benefits from protection
People with fair skin that burns easily are especially sensitive to UV. But UV damages the skin of people of every color.
Darker skin has more natural pigment, which offers some protection, yet people with darker skin still develop skin cancer. So lowering UV exposure is worthwhile for everyone.
The less UV your skin takes in over a lifetime, the lower your skin cancer risk.
Turning this into everyday habits
You do not have to hide from the sun to lower your UV exposure. Small steps add up:
- Seek shade during the strongest midday hours.
- Cover up with clothing, a hat, and sunglasses.
- Use a broad-spectrum sunscreen on skin you cannot cover.
- Skip tanning beds entirely.
Because UV passes through clouds and reflects off water, snow, and sand, these habits matter even on days that do not feel especially sunny.
Words to know
Tap any term to see what it means.
Common questions
What is the difference between UVA and UVB rays?
Both are types of ultraviolet radiation from the sun. UVB rays are the main cause of sunburn and affect the surface of the skin. UVA rays reach deeper and add to skin aging and damage. Both types can harm skin cell DNA and contribute to skin cancer, which is why broad-spectrum protection covers both.
How does UV actually cause cancer?
UV rays can damage the DNA inside skin cells. Cells usually repair this damage, but when the damage builds up faster than it can be fixed, cells can start to grow out of control. Over years, this process can lead to skin cancer.
Are tanning beds safer than the sun?
No. Tanning beds give off UV radiation, and using them raises the risk of skin cancer, including melanoma. The risk is higher for people who start using them at a younger age. There is no safe way to get a tan from UV.
Does a sunburn matter if it fades?
Yes. Even after the redness fades, the DNA damage from a sunburn remains in the skin cells. Blistering sunburns, especially in childhood, are linked to a higher risk of melanoma later in life.
Can I get UV damage without feeling hot?
Yes. UV is invisible and is not the same as heat. You can get significant UV exposure on cool or cloudy days, and UV reflects off snow, water, and sand, adding to your total dose.
Do I still need protection if I rarely burn?
Yes. Tanning without burning still means UV has reached and damaged your skin. People who tan easily and people with darker skin can still develop skin cancer, so limiting UV exposure benefits everyone.
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Last updated: 2026-07-04Next planned review: 2027-07-04
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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