Sunburn is your body’s inflammatory response to excessive ultraviolet (UV) radiation exposure.

When UV rays damage DNA in skin cells, your body increases blood flow to repair the damage. That’s why sunburned skin becomes:

• Red
• Warm
• Painful
• Swollen
• Sometimes blistered or peeling

Repeated or severe sunburn increases the risk of skin cancers, including melanoma.

Types of UV Radiation

• UVA (320–400 nm): Penetrates deep into skin; contributes to aging and long-term damage.
• UVB (280–320 nm): Primarily responsible for sunburn.
• UVC: Blocked by the ozone layer and does not reach Earth’s surface.

2. Skin Type: The Biggest Factor

Your natural skin tone plays a major role in how easily you burn.

Dermatologists use the Fitzpatrick scale to classify skin types: