What Is a Sun Blister?
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Medically reviewed by Brendan Camp, MD
Sun blisters are tiny, fluid-filled bumps that form on the skin due to second-degree sunburns. They develop after too much exposure to the sun's ultraviolet (UV) rays, which burn into the top two layers of skin. You're more likely to get sun blisters if you spend time outdoors without adequate sunscreen or protective clothing.
Sun blisters are often painful and itchy and can ooze fluid when broken open. Depending on the severity, most sun blisters can be treated at home and heal within a few weeks. However, sun blisters can become infected and require medical treatment. Every time you get sun blisters, you also increase your risk of skin damage, premature aging, and skin cancer.
Sun Blister Symptoms
Sun blisters look like small bumps filled with white, yellow, or clear fluid. These can form hours to days after getting a second-degree sunburn. Sunburned skin surrounding the blisters will be deep red or pink and may also be swollen. Sun blisters may also form into a single, large blister. They can cover the entire area of sunburned skin or more severely burned patches, making the skin appear wet or glossy.
Sun blisters often feel tender and painful, especially if touched or rubbed against clothing. This pain may peak 6-48 hours after sun exposure. They are usually extremely itchy, especially as the skin heals. Sun blisters may also break open and ooze fluid. Blisters that pop open or are picked are more likely to scar.
Sun blisters typically heal within 7-10 days but can take up to 21 days. The blisters may form a yellow crust on your skin as they heal. After the blister heals, you may have dark spots (hyperpigmentation), light spots, or scarring. Dark or light spots can be temporary but can take up to six to nine months to resolve.
More severe second-degree sunburns that cause sun blisters can also lead to sun poisoning, which includes symptoms like nausea, fever, and chills.
What Causes Sun Blisters?
Second-degree sunburns cause sun blisters. You can get second-degree burns from natural UV light from the sun or artificial light from tanning beds or sunlamps.
When exposed to UV rays, a protective skin pigment called melanin helps prevent UV rays from penetrating your skin layers. When sun exposure exceeds your skin's ability to produce melanin, UV rays penetrate and burn your skin. Sun blisters occur when UV rays burn the top layer of skin (epidermis) and the middle layer of skin (dermis)—causing a second-degree burn.
Risk Factors
You are more at risk of getting second-degree sunburns and sun blisters if you have a very light skin tone. People with light skin tones can get sunburned in just 15 minutes. These skin types have significantly less melanin than darker skin tones to protect the skin from UV rays. However, people with darker skin tones can also get sun blisters.
Other factors that increase your risk of getting sun blisters include:
Being a child or infant
Spending time outside during peak UV radiation between 10 a.m. and 4 p.m.
Not applying sunscreen or not reapplying it when outdoors for extended periods
Living at higher altitudes or closer to the equator where the sun's rays are stronger
Spending time in water, sand, or snow that reflects additional UV rays onto skin
Using sunlamps or tanning beds
Taking medications that cause sun sensitivity, like the antibiotics doxycycline and tetracycline
Having lupus, which makes your skin more sun sensitive
How Are Sun Blisters Diagnosed?
Sunburns and related sun blisters don't usually require a visit to a healthcare provider for diagnosis. If you see your healthcare provider, they will physically examine your skin for signs of sunburn and blistering. They will also ask about your sun exposure, symptoms, and sunscreen habits. Visually seeing a sun blister and surrounding sunburn is enough to diagnose second-degree burns and sun blisters.
Most sun blisters can be self-diagnosed, but see your healthcare provider if you think your sun blister is infected. In these cases, they may recommend seeking emergency care or seeing a burn specialist. Signs you need to see a provider about an infected sun blister include:
Increasing redness from the edge of the blister or sunburn
Pain that doesn't go away or becomes more intense
Pus-like discharge
Fever above 100.4 degrees
Treatment for Sun Blisters
You can typically treat sun blisters with at-home care to help relieve pain and improve healing. Some basic ways to help treat sun blisters include:
Cool the area: Take a cool, 15-minute shower or bath to soothe the skin. You can also apply clean washcloths soaked in cool water to your sun blisters.
Cover blisters: Place dry "non-stick" bandages over the blisters to help prevent infection. Change the bandages twice a day.
Apply antibiotic ointment: Apply antibiotic ointment like bacitracin to burns with or without a bandage to help prevent infection.
Cover your skin: Wear loose, cotton clothing to protect your skin and let it breathe. Avoid spending time in the sun as your skin heals.
Stay hydrated: Severe blistering can lead to fluid loss and dehydration, so drink plenty of water. You may also need to replace electrolytes with sports drinks or hydration powders.
Avoid oil-based products: Avoid applying petroleum jelly (Vaseline) to skin blisters as well as using DIY treatments made with mayo, butter, egg whites, lavender oil, or toothpaste. These may irritate the skin or lead to infection. You can use a light moisturizer on non-blistered sunburns to soothe the skin.
Take pain relievers: Take over-the-counter (OTC) pain relievers like Advil (ibuprofen) or Tylenol (acetaminophen) to reduce pain.
Do NOT pick blisters: Avoid touching, popping, or scratching blisters. This can increase your risk of infection and scarring.
If you have infected sun blisters, your healthcare provider may prescribe antibiotics to treat an infection. Prescription pain medications can also help alleviate severe pain. In addition, your provider may suggest using OTC antihistamines like Benadryl (diphenhydramine) to help reduce itching.
In cases where second-degree burns cause dehydration, you might be given a special electrolyte fluid solution to help you regain fluids and electrolyte balance.
How To Prevent Sun Blisters
You can prevent sun blisters by protecting your skin from sunburn-causing UV rays. Essential sun protection tips include:
Use sunscreen: Apply a broad-spectrum sunscreen with a sun protection factor (SPF) of 30 or more. Reapply every two hours and after swimming or sweating.
Apply SPF lip balm: Remember to protect your lips from UV rays with a lip balm containing sunscreen.
Avoid tanning beds: Artificial UV rays increase your risk of burns and skin damage.
Wear protective clothing: Wear hats, lightweight long-sleeved clothing, or sun-protective clothing with an ultraviolet protection factor (UPF).
Avoid peak sun hours: Get out of the sun or seek shade between 10 a.m. and 4 p.m.
Complications
Sunburns, in general, increase your risk of premature aging, skin discoloration, and skin cancer. If you have sun blisters frequently, your skin is being continuously damaged by UV exposure, which can lead to melanoma and other skin cancers. However, even short, severe sunburns without blistering are linked to developing melanoma.
Skin cancers and skin conditions linked to sunburn and sun blisters include:
Age spots (liver spots): Flat dark skin patches (hyperpigmentation) caused by sun exposure that typically appear on your face, hands, shoulders, or forearms
Vitiligo: White patches of skin caused by destroyed melanin cells that can't create skin pigment
Actinic keratosis: Precancerous growths that look like dry, scaly spots or patches of skin
Melanoma: Skin cancer caused by melanocytes (cells that make melanin) in the epidermis overgrow, leading to cancerous moles
Basal cell carcinoma: Skin cancer caused by damaged basal cells in the epidermis that grow rapidly into pink patches or flesh-colored round bumps
Squamous cell carcinoma: Skin cancer caused by squamous cells in the epidermis overgrowing into firm red bumps, scaly patches, or sores that heal and re-open
A Quick Review
Sun blisters form from second-degree sunburns caused by UV light. If you have sun blisters, your sunburn affects the epidermis and dermis layers of your skin. Sun blisters are usually very painful and itchy. You can usually treat sun blisters at home, and they'll heal in a week or two. However, if you have severely painful sun blisters and flu-like symptoms, you may have an infection that needs treatment.
Even sun blisters that go away on their own increase your risk of skin cancer and premature aging. Wearing sunscreen and protecting your skin from the sun is the best way to prevent sun blisters.
Frequently Asked Questions
Does drinking water help sun blisters?
Drinking water is important if you are sunburned and have sun blisters. Severe blistering can make you lose fluids and electrolytes. Drinking water will help you replenish fluids and avoid dehydration.
How long does it take for sun blisters to go away?
Sun blisters usually go away on their own in 7-10 days. More severe blisters may take up to 21 days to heal.
Should you cover a sun blister or let it breathe?
You want sun blisters to breathe while they heal. However, you can still cover them with breathable bandages and clothing to help prevent infection. When covering sun blisters, opt for loose cotton clothing and non-stick bandages.
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