Sunburn: Causes, Symptoms & Treatment

The redness of a sunburn comes from the body flooding the area with blood to treat the damage and from inflammation of the skin. (Image credit: Ron Sumners | Dreamstime)

Though sunburn is often laughed off as a side effect of a leisurely visit to the beach or the pool, it can be quite serious. In the United States, over 5.4 million cases of nonmelanoma skin cancer are treated each year and 90 percent of these cancers are associated with exposure to ultraviolet (UV) radiation from the sun, according to the Skin Cancer Foundation


Sunburns all start with melanin and UV rays. The UV rays found in sunlight and tanning beds damage the skin by damaging the DNA inside of cells. Once the DNA is damaged, the cell usually dies. Melanin is the skin's defense against this damage.

When the skin is exposed to the sun, it makes more melanin to protect the skin's lower layers from damage. As the skin becomes damaged, it produces even more melanin. The extra melanin causes some people to become a darker color, or tan. Other people turn red, which is a sign of a sunburn. The redness of a sunburn comes from the body flooding the area with blood to treat the damage and from inflammation of the skin. 

"Melanin is a natural sunscreen," said Gary Chuang, an assistant professor of dermatology at Tufts University School of Medicine. "When your body senses sun damage, what it does is, it starts sending out melanin into surrounding cells and tries to protect them and shield them from getting more damage." [Science of Summer: What Causes Sunburns?]

To protect the skin, the melanin absorbs the UV light. Then, it disperses it as heat.

Melanin is also what makes people have light or dark skin. People with light skin have very little melanin while people with dark skin have a lot of melanin. How long a person spends in the sun, combined with their skin type, determines if and when a person burns. Darker people don't sunburn because they have more natural sunscreen than those with less melanin.

Dermatologists use the Fitzpatrick Scale to determine a person's risk of sunburn by their skin type, according to Dr. Sharad P. Paul. Paul is a skin cancer specialist, skincare expert, evolutionary biologist, author and an adjunct professor at Auckland University of Technology.

Here is how the Fitzpatrick Scale works:

  • Type 1 skin always burns and never tans, which is typical of redheads and platinum blondes. These people can spend a maximum time of 67 minutes, unprotected, in the sun divided by the UV index at that time. So, if the UV index is 12, the person can spend 5.85 minutes in the sun, unprotected, before burning.
  • Type 2 skin burns easily, but tans with difficulty. This is usually typical of blondes and those who are blue-eyed. Skin type 2 can spend a maximum time of 100 minutes divided by the UV index in the sun without burning.
  • Type 3 skin rarely burns and tans easily. This skin type usually belongs to those with brown or black hair and those with brown eyes. Skin type 3 can spend a maximum of 200 minutes divided by the UV index in the sun without burning.
  • Type 4 skin burns sometimes and tans easily. These people are usually of Mediterranean, Spanish or Indian decent. Skin type 4 can spend a maximum time 300 minutes divided by the UV index in the sun without burning.
  • Type 5 skin is dark brown and never burns, but tans easily. This is typical of darker Indian skin and some North African skin.
  • Type 6 is skin that has a lot of melanin and does not burn. This skin also tans easily, though it is hard to see since the skin is already so dark. 


Symptoms of a sunburn, which typically start a few hours after exposure, include hot, pink or red skin that can be tender to the touch. Some swelling may also occur. In severe cases, the person may experience headache, fever, fatigue and chills, according to the Mayo Clinic.

In second-degree burns, the skin may form liquid-filled boils as a way to cool down the area. "If the blisters cover a large area, such as the entire back, or you have chills, a headache or a fever, seek immediate medical care," Dr. Delphine J. Lee, a dermatologist at Providence Saint John's Health Center in Santa Monica, California, told Live Science.  

Symptoms of sunburn can last for days as the skin repairs. The worse the burn, the longer the healing will take. Typically, a sign that the end is near is the damaged areas peeling and falling off.

Sunburn doesn't only happen to skin, though. Eyes can also be sunburned. Sunburned eyes often feel gritty or painful, according to the Mayo Clinic.


Treatment should start as soon as the person realizes they are burnt. "First, stop further ultraviolet light exposure by getting out of the sun," said Lee. Staying out of the sun while the burn heals is also important.

Lee also advises soaking in cool water to help reduce skin temperature and help soothe the skin. After soaking, pat the skin dry with a towel, but leave some water on the skin. Then apply a moisturizer to trap the last few water molecules remaining on the skin. This will help prevent dryness, which can cause more discomfort. Do not peel the skin off as the sunburn heals. Let the dead skin fall off naturally. A hydrocortisone cream from the drugstore can help ease discomfort.  

Over-the-counter pain relievers such as aspirin or ibuprofen can help reduce swelling, redness and discomfort. "Be sure to ask your board-certified dermatologist if you have other medical conditions or are unsure of the proper dose of these medications," said Lee.  

It is also important drink extra water to prevent dehydration, since the sunburn draws fluid to the skin surface and away from the rest of the body.  


"The best way to approach a sunburn is to prevent it," said Lee. To prevent sunburns, Lee suggests avoiding the sun by seeking shade (especially when the sun's rays are the strongest from 10 a.m. to 2 p.m.), cover up with sun-protective clothing and a hat and wear sunscreen. "A shot glass (1 ounce) of sunscreen is an adequate amount to be used when most of your skin is exposed while wearing a swimsuit and should be reapplied every two hours," said Lee.

Sun-protective swimwear and UV blocking tint on car and home windows can also prevent unintentional burns. These can be particularly helpful for those who easily burn.

Sunglasses that block 100 percent of UV rays is key to preventing eye burn and damage to the eye.

Don't think that clouds prevent sunburns. Eighty percent of the UV rays still get through the clouds, so protection is needed on those days, too, according to the American Academy of Dermatology. Also, be especially careful around ice, snow and water, as they can reflect sunlight. Snow can actually double a person's exposure to UV rays, according to the Environmental Protection Agency (EPA).

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Alina Bradford
Live Science Contributor
Alina Bradford is a contributing writer for Live Science. Over the past 16 years, Alina has covered everything from Ebola to androids while writing health, science and tech articles for major publications. She has multiple health, safety and lifesaving certifications from Oklahoma State University. Alina's goal in life is to try as many experiences as possible. To date, she has been a volunteer firefighter, a dispatcher, substitute teacher, artist, janitor, children's book author, pizza maker, event coordinator and much more.