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Sunburn is a skin injury caused by heat and radiation. A first-degree burn affects the top layer of the skin and causes redness, slight tenderness, and may cause light peeling of the skin within 24 to 48 hours after injury.

A more serious sunburn, known as a second-degree burn, causes damage deeper in the skin. This type of burn may cause blisters to form and takes longer to heal. The blisters usually appear a few hours after sunburn occurs, but sometimes they can take up to 24 hours to develop.

Sunburn blisters can be extremely painful and take around a week to heal. This type of burn also increases the risk of developing skin cancer and melanoma. After the blisters heal, blister scars that appear as dark or light spots on the surface of the skin can remain visible for 6 to 12 months.

In this article, we look at what causes these blisters to form, how to look after them, and what can be done to protect the skin from the sun.

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A second-degree burn from sun exposure may cause sunburn blisters.
Image credit: Axelv, 2008

Sunburn blisters form as small bumps on the skin.

They are usually white or transparent in appearance and filled with fluid, which can be lymph, serum, plasma, blood, or pus.

Most people who get sunburned will find the blisters very painful, particularly if touched or if an item of clothing rubs against them. They may also become extremely itchy.

However, both pain and itchiness will lessen as the blisters start to heal.

Possible complications

Sunburn blisters usually only ever occur when a person has been severely sunburned. Because of this, several complications can arise in a person who develops blisters due to overexposure to the sun.

These complications include:

Anyone who experiences these symptoms after being in the sun should seek advice from their doctor, regardless of whether sunburn blisters appear or not.

Sunburn blisters alone have few complications, though an infection may occur if they are picked at or popped. An infection could require medical treatment and will likely lead to scarring.

Because sunburn blisters usually only occur in people with bad sunburn, there is also an increased risk of skin cancer.

Many people with sunburn blisters find that they heal naturally and will disappear by themselves after about a week.

However, if a person is uncertain whether the lumps on their skin are sunburn blisters, they should visit a doctor or a dermatologist who will examine them and make a diagnosis based on the appearance of the lumps. The doctor or dermatologist can then offer possible treatment options and advice.

A person with sunburn blisters should visit their doctor immediately if they also experience any of the following symptoms:

  • swelling of the skin
  • chills or a high temperature (100°F or higher)
  • dizziness, a severe headache, nausea, or vomiting

The doctor will ask questions such as how long they were in the sun and whether they used any sun protection. They will then be able to advise the individual on the best course of action.

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Applying lotions that include aloe vera may help to relieve sunburn.

Sunburn that is bad enough to cause blistering may require professional medical treatment.

A doctor may prescribe special burn cream to soothe the skin and help with the healing process and may also apply a dressing to protect the area.

If a person displays any of the associated sun poisoning symptoms, they may need to stay in the hospital to enable doctors to monitor them more closely.

Treating milder cases of sunburn at home is possible. It is essential to get indoors and out of the sun as soon as sunburn occurs.

Other home care options include:

  • Cooling skin by having a cold bath or shower, or simply using a cold damp sponge or flannel can help soothe skin and relieve pain and itching.
  • Applying lotions designed to relieve sunburn, such as those containing aloe vera, can also be helpful by soothing the skin and keeping it moisturized. Aloe vera gel is available for purchase online.
  • Drinking plenty of hydrating fluids, such as water, will cool the body and prevent dehydration.
  • Taking painkillers available for purchase over the counter or online, such as ibuprofen or acetaminophen, to help relieve pain.
  • Remaining in a cool, shaded room away from direct sunlight.
  • Covering up all affected areas and ensuring they are not exposed to the sun until the skin has fully healed.

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Protecting the skin with a sunscreen that has a high sun protection factor (SPF) is recommended to avoid sunburn.

The easiest way to avoid sunburn blisters is to stay out of the sun. However, this is not always practical or possible.

The most common ways to prevent sunburn blisters are:

  • Avoiding going outside during the times when the sun is at its strongest.
  • Protecting skin from the sun even on cloudier days will help to ensure it does not burn.
  • Using a sunscreen that has a sun protection factor (SPF) of 30 or above and applying this every 2 hours when out in the sun. SPF 30 sunscreen is available for purchase online.
  • Wearing protective clothing, such as long-sleeved shirts or T-shirts, sunglasses, and wide-brim hats, will also give added protection.
  • Applying sunscreen generously, making sure to cover every part of the body.
  • Buying sunscreen that blocks both ultraviolet A (UVA) and ultraviolet B (UVB) radiation and has a minimum 4-star rating for UVA protection.
  • Re-applying sunscreen after entering the water or excessive sweating, even if the label says the product is water-resistant.

A person should also be aware of their skin’s sensitivity to the sun. This sensitivity varies from person to person, but typically fairer skinned people are likely to burn more quickly.

Some medicines can increase a person’s sensitivity to the sun and therefore the chances of them burning. People should be sure to read the labels of any medications before being in the sun for long periods of time and seek advice from a doctor if unsure.

Sunburn blisters can occur even in cooler, cloudier conditions, and light reflected off snow can also increase the risk of sunburn.

The dangers of exposure to harmful UV rays from the sun can result in more serious long-term effects, many of which will not become apparent until decades later

These long-term effects can include:

  • Precancerous spots known as solar keratosis can appear on the skin and will usually be dark, rough, and scaly in appearance.
  • Premature aging of the skin can occur on skin exposed to lots of sun along with dark sunspots.
  • Skin cancer is another risk, particularly to those who burn their skin severely enough that sunburn blisters occur.

For many people with sunburn blisters, however, home care treatment options are enough to ensure that they recover well.

As long as sunburn blisters heal, are not picked at or popped, and do not become infected, they should go away and fade with time.