Sunburn is the skin’s reaction to too much exposure to ultraviolet (UV) radiation from the sun. You can see sunlight and feel heat (infrared radiation), but you can’t see or feel UV radiation. It can damage your skin even on cool, cloudy days.
Sunburn is a radiation burn to the skin. The signs of sunburn can start to appear in as little as 11 minutes and skin can turn red within 2 to 6 hours of being burnt. It will continue to develop for the next 24 to 72 hours and, depending on the severity, can take days or weeks to heal.
Sunburn will become worse with more exposure to UV rays. Mild sunburn can be treated at home, but severe and blistered sunburn requires prompt medical attention.
The long-term effects of repeated bouts of sunburn include premature wrinkling and an increased risk of skin cancer, including melanoma (the most dangerous type of skin cancer). DNA in cells may be damaged, and, if not repaired by the body repeatedly over time, abnormal cells may develop, leading to cancer. This is why prevention is very important.
Risk of sunburn is increased in regions that are closer to the equator and that are higher in altitude. Lighter-skinned individuals are affected more frequently and severely. Skin types are traditionally classified into the following Fitzpatrick categories, based on an individual’s tendency to tan, burn, or both.
UVA and UVB rays both play a role in sunburn, though UVB rays are responsible for directly damaging DNA by inducing the formation of thymine-thymine cyclobutane dimers. When these dimers are formed, the body generates a DNA repair response, which includes the induction of apoptosis of cells and the release of inflammatory markers such as prostaglandins, reactive oxygen species, and bradykinin. This leads to vasodilation, edema, and pain which translates into the classically red, painful skin seen in a sunburn. Additionally, skin exposure to UVB causes an increase in chemokines such as CXCL5 and activates peripheral nociceptors, which results in over-activation of the pain receptors of the skin.
Types of Sunburn
The least harmful burn is the first-degree burn, also called superficial skin burn. This burn makes your skin red, dry, and painful when you touch it. This is the most common type of sunburn and can heal within 3 to 6 days.
First-Degree Sun burn
The second-degree type of burn, also called superficial partial-thickness burn, effects the top two layers of your skin. It will hurt if the temperature changes or if you touch it. You may see blisters appear on your burn, which hold leak fluid. This type of sunburn will heal in 7 to 21 days and the color of the original skin may be lighter or darker. You might develop a scar with this type of burn.
Second-Degree Sun burn
The third-degree burn, also called deep partial-thickness burn, is deeper than the second-degree burn and is more severe. This burn will most definitely give you blisters and takes even longer to heal. This burn will give you a scar if it doesn’t heal by the 21st day.
Third-Degree Sun burn
The last type of burn is very serious and to be avoided at all costs. This is the fourth-degree burn, also called full-thickness burn, and it would be treated like a surgery. It affects all the layers of skin and possibly the fat and muscle underneath as well. This burn makes the skin turn a different color, normally white, grey, or black! You could end up in the hospital for days taking medications. To say this would put a damper on your vacation would be an understatement – this type of burn can cause severe long term damage to your skin.
Sunburn damage may cause different types of sunburn ranging from very mild redness to excruciating vast burn with blistering but rarely reaches the deep-partial thickness type of burn.
Sunburn risk factors
Certain factors increase the risk of sunburn. These include:
- Being outdoors when the UV index is highest, between the hours of 10 a.m. and 4 p.m.
- Having fair skin, blue eyes, freckles, or red or blonde hair
- Being outdoors at higher altitudes, such as when skiing or hiking
- Working or playing sports outdoors
- Being closer to the equator
Younger people are at high risk. One 2017 survey, found that around 50% of high school boys and 60% of high school girls had experienced sunburn in the previous 12 months.
Although people with dark skin are at relatively lower risk of burning, they should still take adequate measures to stay safe from sunburn.
Causes of Sunburn
Intense, repeated sun exposure that results in sunburn increases your risk of other skin damage and certain diseases. These include premature aging of skin (photoaging), precancerous skin lesions and skin cancer.
Premature aging of your skin
Sun exposure and repeated sunburns accelerate the skin’s aging process, making you look older than you are. Skin changes caused by UV light are called photoaging. The results of photoaging include:
- Weakening of connective tissues, which reduces the skin’s strength and elasticity
- Deep wrinkles
- Dry, rough skin
- Fine red veins on your cheeks, nose and ears
- Freckles, mostly on your face and shoulders
- Dark or discolored spots (macules) on your face, back of hands, arms, chest and upper back also called solar lentigines
Precancerous skin lesions
Precancerous skin lesions appear as rough, scaly patches in areas that have been damaged by the sun. They’re usually found on the sun-exposed areas of the head, face, neck and hands of light-skinned people. These patches can evolve into skin cancer. They’re also called actinic keratoses (ak-TIN-ik ker-uh-TOE-seez) and solar keratoses.
Excessive sun exposure, even without sunburn, increases your risk of skin cancer, such as melanoma. It can damage the DNA of skin cells. Sunburns in childhood and adolescence may increase your risk of developing melanoma later in life.
Skin cancer develops mainly on areas of the body most exposed to sunlight, including the scalp, face, lips, ears, neck, chest, arms, hands, legs and back.
Some types of skin cancer appear as a small growth or a sore that bleeds easily, crusts over, heals and then reopens. With melanoma, an existing mole may change, or a new, suspicious-looking mole may develop. A type of melanoma called lentigo maligna develops in areas of long-term sun exposure. It starts as a tan flat spot that slowly darkens and enlarges.
See your doctor if you notice a new skin growth, a bothersome change in your skin, a change in the appearance or texture of a mole, or a sore that doesn’t heal.
The sun can also burn your eyes. Too much UV light damages the retina, lens or cornea. Sun damage to the lens can lead to clouding of the lens (cataracts). Sunburned eyes may feel painful or gritty. Sunburn of the cornea is also called snow blindness.
Symptoms of Sunburn
These are the most common symptoms of sunburn:
- Swelling of the skin
Dry, itching, and peeling skin 3 to 8 days after the burn
More severe cases may cause:
- Weakness, confusion, or faintness
The symptoms of sunburn may look like other skin conditions. Always see your child’s healthcare provider for a diagnosis if you are unsure.
- Heatstroke or dehydration
- Secondary infection of the burn
- Exacerbation of some dermatological conditions
- Premature ageing, solar keratoses, basal cell carcinoma, squamous cell carcinoma of skin and malignant melanoma of skin are associated with sun exposure
- Photosensitivity reactions
Diagnosis and test
Your doctor is likely to conduct a physical exam and ask questions about your symptoms, UV exposure and sunburn history.
If you develop a sunburn or skin reaction after minor exposures to sunlight, your doctor might recommend a test where small areas of skin are exposed to measured amounts of UVA and UVB light to try to mimic the problem (phototesting). If your skin reacts to the UV light, you’re considered sensitive to sunlight (photosensitive).
Treatment and medications
Sunburn treatment is designed to attack the burn on two fronts relieving reddened, inflamed skin while easing pain. Here are a few home remedies for sunburn:
Compresses: Apply cold compresses to your skin or take a cool bath to soothe the burn.
Creams or gels: To take the sting out of your sunburn, gently rub on a cream or gel containing ingredients such as:
Refrigerating the cream first will make it feel even better on your sunburned skin.
NSAIDs: Nonsteroidal anti-inflammatory drugs, like ibuprofen or naproxen, can relieve sunburn swelling and pain all over your body.
Stay hydrated: Drink plenty of water and other fluids so that you don’t become dehydrated.
Avoid the sun: Until your sunburn heals, stay out of the sun.
You may be able to treat the sunburn yourself. But call for a doctor’s help if you notice any of these more serious sunburn signs:
- Fever of 102 degrees or higher
- Severe pain
- Sunburn blisters that cover 20% or more of your body
- Dry mouth, thirst, reduced urination, dizziness, and fatigue, which are signs of dehydration
Prevention of Sunburn
A main way to prevent sunburn is to wear sunscreen and protective clothing. Sunscreens are chemicals that block or filter sunlight. Sunscreen comes in lotions, creams, sprays, and powders. Some have chemicals that absorb and filter the sunlight, such as oxybenzone and avobenzone. Others have chemicals that physically block the light, such as zinc oxide or titanium dioxide. No sunscreen blocks 100% of UV light. But they help protect the skin.
When using sunscreen:
- Wear sunscreen with a sun protection factor (SPF) of 30 or higher.
- Pick broad spectrum sunscreen that blocks both UVA and UVB rays.
- Use a waterproof or water-resistant sunscreen.
- Apply to all exposed skin, including ears, lips, back of the neck, and tops of the feet.
- Apply it 30 minutes before going outside.
- Reapply it every 2 hours, or after swimming, exercising, or sweating.
Other ways to prevent sunburn include:
- Stay out of the sun from 10 a.m. to 4 p.m. This is when the sun’s UV rays are strongest.
- Wear a hat with a wide brim.
- Wear clothing that protects your skin from the sun. Some clothing is rated with UV protection factor (UPF).
- Don’t use a tanning bed.
- Look for shade. Shaded areas get less UV radiation.
- Use sunscreen even in the shade. UV rays are reflected off other surfaces such as sand, snow, cement, and water.