PolitiFact – Wear your sunscreen. The sun does not prevent skin cancer.

Sun exposure is important to our well-being, given that it stimulates production of vitamin D and positively affects our mood. 

One thing it doesn’t do is prevent sun cancer, despite a viral Facebook post.

“They told us ‘The sun will give you skin cancer’ but in reality the sun prevents skin cancer!” a May 8 post read.

The post was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)

So, should you skip the sunscreen? No. Scientific evidence overwhelmingly shows that excessive exposure to ultraviolet radiation — which the sun emits — is a risk factor for skin cancer. Health institutes widely recommend protecting your skin from sunlight. 

“The sun is the cause of, not a treatment for, skin cancer. It is a matter of incontrovertible scientific truth that UV from the sun (or artificial sources like tanning beds, for that matter) causes mutations in cancer-causing genes in the skin,” said Dr. David Leffell, a professor of dermatology and surgery at Yale School of Medicine.

The Centers for Disease Control and Prevention and American Cancer Society offer more warnings: Most skin cancers are caused by too much exposure to UV light, and sunlight is the main source of UV radiation. 

Other sources of ultraviolet rays include sunlamps, tanning beds and black-light lamps.

Although small amounts of ultraviolet radiation are essential for vitamin D production, overexposure may harm the skin, eyes and immune system, according to the World Health Organization’s International Agency for Research on Cancer.

The development of skin cancers such as basal and squamous cell carcinomas is linked closely to ultraviolet exposure. These are the most common types of skin cancer, and they tend to be found on sun-exposed parts of the body, typically related to lifetime sun exposure.

People of all ages and skin tones should limit time spent in the sun, especially between midmorning and late afternoon, the National Cancer Institute said. Sunscreen (with a sun protection factor of at least 15) should be applied to uncovered skin 30 minutes before going outside, with reapplication every two hours or after swimming or sweating.

You can get enough vitamin D by getting up to 15 minutes of casual sun exposure on your face, arms and hands for two to three days a week in the summer, according to WHO guidance. Avoiding the sun entirely could risk bone health. 

We rate the claim that the sun prevents skin cancer False.