How Skin Tans: Melanin & UV Exposure

A UV tan is a change in skin colour following ultraviolet exposure. It involves melanin, the pigment associated with skin colour, but colour alone cannot tell you whether exposure has been safe.

How do UVA and UVB affect a tan?

UVA can darken melanin already present in skin. UVB can stimulate the production of new melanin over the following days. The World Health Organization's explanation of UV effects describes how these responses differ.

Does a tan protect the skin?

A UV tan is a response to damage. WHO explains that it does not defend against the long-term effects of UV, including skin cancer. It should not be treated as preparation that makes later exposure safe.

Is sunburn the only sign of damage?

No. Visible burning is not the only concern. Cancer Research UK explains that UV can damage DNA in skin cells and that damage can build up over time. People of every skin tone can develop skin cancer.

Explore UVA and UVB in more detail or read our sun-protection guide and tanning FAQs.

Information checked against the linked sources on 2 October 2026.