A sunburn is skin damage from the sun's ultraviolet A and ultraviolet B (UVA and UVB) rays. Most sunburns cause mild pain and redness but affect only the outer layer of skin (first-degree burn). The red skin might hurt when you touch it. These sunburns are mild. They can usually be treated at home.

Skin that is red and painful and that swells up and blisters may mean that deep skin layers and nerve endings have been damaged (second-degree burn). This type of sunburn is usually more painful and takes longer to heal.

Other problems that can occur along with sunburn include:

• Heatstroke or other heat-related illnesses from too much sun exposure.
• Allergic reactions to sun exposure, sunscreen products, or medicines, such as antibiotics, some acne medicines, and some diabetes medicines.
• Vision problems, such as burning pain, decreased vision, or partial or complete vision loss.

Long-term problems include:
• An increased chance of having skin cancer.
• Having more cold sores.
• More risk of problems related to a health condition, such as lupus. • Cataracts from not protecting your eyes from direct or indirect sunlight over many years. Cataracts are one of the leading causes of blindness.
• Skin changes, such as premature wrinkling or brown spots.

People with white or freckled skin, blond or red hair, and blue eyes usually sunburn easily.
People with darker skin don't sunburn as easily. But they can still get skin cancer. It is important to use sun protection, no matter what your skin colour is.

Your age also affects how your skin reacts to the sun. Children's skin is more sensitive to sunlight.

You may get a more severe sunburn depending on:
• The time of day. You are more likely to get a sunburn between 11 a.m. in the morning and 3 p.m., when the sun's rays are the strongest. You might think the chance of getting a sunburn on cloudy days is less, but the sun's damaging UV light can pass through clouds.
• Whether you are near reflective surfaces, such as water, white sand, concrete, snow, or ice. All of these reflect the sun's rays and can increase your risk of getting a sunburn.
• The season. The position of the sun on summer days can cause a more severe sunburn.
• Altitude. It's easy to get sunburned at higher altitudes. That's because there's less of the earth's atmosphere to block the sunlight. UV exposure increases in elevation.
• How close you are to the equator (latitude). The closer you are to the equator, the more direct sunlight passes through the atmosphere.
• The UV index of the day, which shows the risk of getting a sunburn that day.

Preventive measures and home treatment are usually all that's needed to prevent or treat a sunburn.
• Protect your skin from the sun.
• Don't stay in the sun too long.
• Use sunscreen and wear clothing that covers your skin.