Condition

Sunburn

Sunburn is an injury to the skin from ultraviolet light. The redness and pain are the body clearing away damaged cells, which is why they arrive hours after the exposure rather than during it. The skin heals in about a week. Some of the DNA damage underneath does not.
Dr. Schwarz, MD · Board-certified dermatologistLast reviewed September 8, 2026
16:9 hero for Sunburn. Never cropped: the tone strip and the corner logo depend on the full frame.

Start here

The surprise is the delay - you do not feel a sunburn happening, and by the time the redness appears three or four hours later and peaks the next morning, the decision was made hours ago. So sun protection has to be planned, not reactive. Treating a burn is genuinely limited - cool compresses, an anti-inflammatory painkiller early, fluids, moisturizer and time - and anyone selling you something that reverses a burn is selling you something.

What I take seriously is the pattern - one bad burn is bad luck, but burning most summers for decades is what turns up in my clinic thirty years later as precancers and skin cancers.

— Dr. Schwarz, Board Certified Dermatologist

Key Facts

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How commonVery common. A large share of adults in the United States report at least one sunburn in a given year
Who gets itAnyone. It happens faster and more easily in fair skin that burns rather than tans, but every skin tone can burn
Curable or managedThe burn heals on its own. The DNA damage it causes adds permanently to lifetime skin cancer risk
Prescription neededNo, for most burns. Severe, widespread or blistering burns and any signs of heat illness need medical care
Time to improveRedness appears within 2 to 6 hours and peaks around 12 to 24 hours. Most burns settle over 3 to 7 days, with peeling toward the end

What It Is

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Sunburn is an inflammatory reaction to skin cells damaged by ultraviolet light, mainly UVB, with UVA contributing.

The sequence explains the timing. Ultraviolet light damages DNA inside skin cells, cells too damaged to repair are triggered to die, and the immune system answers with inflammation - vessels widen, fluid moves into the tissue, pain nerves are sensitized. That takes hours. Redness usually appears two to six hours after exposure, peaks between twelve and twenty-four hours, then fades over several days.

A mild burn is warm, tender, red on lighter skin and dusky, violet or darker on deeper skin tones, and it usually peels a few days later. Peeling is sheets of dead cells shed after the layer beneath has been replaced. A more severe burn swells and blisters, which means the injury went deeper, and it hurts much more.

A large burn can make you unwell as a whole. Fever, chills, headache, nausea, weakness and dehydration are common with extensive burns, sometimes called sun poisoning - not poisoning, but the systemic effect of a large area of inflamed skin plus fluid loss and heat.

The part that matters most is invisible. Some DNA damage is repaired imperfectly and the errors accumulate over a lifetime. That is the link between sunburn and skin cancer. Burns in childhood and adolescence appear to count for more, and repeated blistering sunburns carry a substantially higher risk of melanoma later.

Two things get mistaken for sunburn. Some medicines and plant saps make skin react far more strongly than expected, giving a burn out of proportion to the exposure. And itchy bumps on sun-exposed skin, rather than uniform redness, are usually a light-sensitivity condition.

Symptoms

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Pink, warm, tender

Mild

Skin that is pink or feels hot and tender within hours of sun exposure, settling over a few days and often peeling at the end. In deeper skin tones burn may show as tightness, warmth and soreness rather than obvious redness. Cool compresses and moisturizer are the mainstay.
Bubbles and severe pain

Blistering

Painful blisters over burned skin, meaning a deeper burn. Blisters should be left intact where possible to protect the skin underneath. Large or widespread blistering needs medical care.
Sun poisoning

With Feeling Unwell

Burn along with chills, fever, headache, nausea or dizziness, which points to heat illness and dehydration rather than skin damage alone. This needs fluids, shade and often medical assessment. Children and older adults are affected sooner.

Where It Shows Up

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Front view of a head with red marks on the nose, both ears, both cheekbones, the forehead, the parting of the scalp and the lower lip.
Nose, ears and the parting of the hair
The parts angled at the sun catch it first: the nose, the tops of the ears, the cheekbones and the forehead, plus the parting of the hair on a bare scalp. The lips burn too and are almost never covered.
Back view of a whole body with red marks on the back of the neck, across both shoulders and down the upper and middle back, stopping in a sharp line. The lower body is clear.
Back of the neck, shoulders and upper back
Sunburn appears exactly where the skin was uncovered, and it stops in sharp lines at a collar, a sleeve, a waistband or a swimwear strap. The back of the neck, the shoulders and the upper back take the most, because they face the sun for the whole day.
Front view of a whole body with red marks across the upper chest, down the fronts of both thighs and shins, and on the tops of both feet.
Chest, legs and the tops of the feet
The tops of the feet are the classic missed spot, especially in sandals, and the front of the shins burn in anyone sitting outside. The chest catches it under an open collar.

What Happens in the Skin

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This is what is going wrong under the skin, in the order it happens. Click a step to see it.

How Sunburn happens
Skin basics
BARRIEREPIDERMISDERMISBLOOD VESSELS0NORMAL SKIN1MORE UV LANDS THAN THE SKIN CAN ABSORB2THE SKIN RAISES THE ALARM3BLOOD VESSELS OPEN UP

Pigment in the upper layer absorbs some ultraviolet light, and a network of small blood vessels sits quietly underneath.

Ultraviolet light reaches the living cells below the surface and damages the DNA inside them. This happens while you are still outside and feeling fine.

Damaged cells release signals that call the immune system in. That takes several hours, which is why a burn shows up in the evening rather than on the beach.

Vessels in the deeper layer widen to bring blood to the area. That is the redness, the heat and the tight, swollen feeling. Cells too damaged to repair are shed a few days later, which is the peeling.

The outer film of dead cells and oil. It holds water in and keeps irritants out, and it is thinner than a sheet of paper. Almost every dry, itchy, stinging skin problem starts here.

The outer layer, and the only one anything in a jar reaches. It renews itself constantly: a cell made at the bottom takes about a month to reach the surface and flake off. Most of what a skincare product does, it does here.

The living layer underneath, holding the blood vessels, the nerves and the collagen. It is where lasting change happens and it is hard to reach: most of what is sold for the skin never gets this far.

Ultraviolet light causes it, chiefly UVB, which is absorbed directly by DNA in the cells of the outer skin layer and produces specific errors in it. UVA goes deeper, generates reactive molecules that damage cells indirectly, and adds to burning, aging and cancer risk.

The body responds three ways. It repairs what it can. It kills cells too damaged to repair, and those dying cells trigger the inflammation you see as redness, heat, swelling and pain. Over the next few days it thickens the outer layer and makes more melanin - the tan, which is an injury response, not a sign of health.

How fast you burn depends on the dose arriving and the protection you have. Intensity rises at midday, closer to the equator, at altitude and in summer, and it reflects off water, sand, concrete and especially snow, so exposure can be far higher than your time in direct sun suggests. Up to about 80 percent passes through light cloud. Water barely filters it, so swimming is not shelter. Protection is mostly melanin, which is why fair skin that freckles and burns reaches the threshold faster - that changes how long it takes, not whether it happens.

Some things lower the threshold. Common medicines can increase sensitivity to ultraviolet light, so a normal amount of sun causes an abnormal burn. Certain plant saps do the same on contact, notably lime juice, which leaves oddly shaped burns and dark streaks. Recent peels, laser treatment or retinoid use leave skin more vulnerable too.

Risk Factors

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Some of these are about your skin and some about the situation. The situational ones cause most burns.

Sun exposure
Midday sun
Ultraviolet is strongest roughly between 10 in the morning and 4 in the afternoon; a short exposure then does more than a long one at dusk.
Sun exposure
Altitude, latitude and season
Exposure rises with altitude, closer to the equator, and in summer.
Sun exposure
Reflective surfaces
Snow, water, sand and concrete bounce ultraviolet light back onto skin, including under a hat brim.
Sun exposure
Cloud cover that feels safe
Much of it passes through light cloud, and without the heat the warning is gone.
Sun exposure
Being in water
Water offers minimal protection, and the cooling removes the cue that sends you into the shade.
Sun exposure
Tanning beds
A concentrated dose causing the same injury as the sun.
Inherited & age
Fair skin that burns rather than tans
Skin that freckles, with red or blond hair and light eyes, burns soonest. Every skin tone burns, this one first.
Inherited & age
Infancy and childhood
A baby's skin is thinner and burns faster. Infants under six months should be kept out of direct sun rather than covered in sunscreen.
Medicines & sensitivity
Light-sensitizing medicines
Doxycycline, some blood pressure medicines, retinoids and amiodarone all raise how strongly skin reacts. Ask your doctor.
Medicines & sensitivity
Recent skin treatments
Chemical peels, laser, microneedling and retinoids leave skin more sensitive for a while.
Medicines & sensitivity
Plant sap on the skin
Lime and lemon juice, wild parsnip, giant hogweed and celery cause exaggerated burns in streaks.
Medicines & sensitivity
Certain medical conditions
Lupus, porphyria, albinism, xeroderma pigmentosum and others cause burning at much lower exposures.

Course

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The worst of a sunburn arrives after you have gone indoors. Nothing makes it heal faster - aftercare makes the week bearable and prevents complications, but does not undo the injury. The DNA damage does not fully reverse, and repeated burns, particularly in childhood and adolescence, contribute to actinic keratoses, squamous cell carcinoma, basal cell carcinoma and melanoma decades later.

Nothing visibleDuring exposure
The damage is already happening

No redness and often no discomfort, which is the whole problem with waiting to feel it.

Appearing2 to 6 hours after
Pink or darker, warm and tight

Skin starts to look pink or darker and feels warm and tight. On deeper skin tones this is felt rather than seen.

Peak, and blisters12 hours to day 3
The worst of it

Redness, heat, tenderness and swelling peak, and the burning disturbs sleep. Deeper injury brings small blisters over the next day or two. Fever, chills, headache, nausea or weakness with a large burn means it should be assessed.

PeelingDay 3 to 8
The outer layer sheds

The damaged outer layer sheds in sheets. The new skin underneath is thin, pink and very sensitive to sun and products.

SettlingWeek 2 onward
Discomfort goes, marks can stay

Discomfort resolves. Skin can look uneven, and dark patches may appear where the burn was. On deeper skin tones especially these take many months to fade, and further sun makes them last longer.

What Makes It Better & Worse

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Almost everything that helps happens at step one, before the burn. Past step two the options are comfort only.

What is driving yours?

FATBLOOD VESSELSBARRIEREPIDERMISDERMIS

What helps

  • Get out of the sun and stay out More exposure deepens the injury.
  • Broad-spectrum sunscreen, SPF 30 or higher A teaspoon for the face and neck, two tablespoons for the body, every two hours.
  • Clothing, a wide-brimmed hat and shade More reliable, because they do not wear off.
  • Planning around midday Outdoor time before 10 in the morning or after 4 removes most of the risk.

What makes it worse

  • Not using enough sunscreen Most people apply a quarter to half of what testing assumes.
  • Not reapplying About every two hours, and after swimming or sweating.
  • Assuming cloud is protection Much of the ultraviolet passes through it.
  • Reflected light from water and snow It reaches skin that shade would cover.
  • Midday sun, altitude and the equator The same time in the sun does more damage.
  • Staying in water because it feels cool Water barely filters ultraviolet light.
  • Going back out on burned skin Damaged skin has no protection left.
  • Tanning beds The same injury, delivered deliberately.

What helps

  • Check your medicines for sun sensitivity A question to the pharmacist prevents a whole category of burn.

What makes it worse

  • Light-sensitizing medicines A normal amount of sun produces an abnormal burn. Ask your prescriber about precautions, not stopping anything.
  • Lime juice, hogweed and plant saps Exaggerated burns in streaks where the sap landed.
  • Recent peels, lasers or retinoid use Freshly treated skin burns at much lower exposures.

What helps

  • Cool compresses and cool showers The best thing for pain on day one.
  • An anti-inflammatory painkiller early Better in the first hours than on day two. If you are pregnant or breastfeeding, ask the doctor managing your pregnancy which pain relief is appropriate.
  • Drink more fluid than usual Burned skin pulls fluid out of circulation.
  • A plain, fragrance-free moisturizer Apply while the skin is still damp.
  • Low-strength hydrocortisone cream One percent takes the edge off small areas for a few days.
  • Leave blisters intact If one opens, keep it clean, with petrolatum and a non-stick dressing.
  • Plain petrolatum on peeling skin Stops new skin cracking and reduces itching.
  • Loose cotton clothing Less rubbing on inflamed skin.

What makes it worse

  • Popping blisters Opening them invites infection and can turn a clean burn into a scar.
  • Hot showers, scrubbing and exfoliating Heat and friction increase pain and redness.
  • Numbing sprays Benzocaine and lidocaine cause allergic rashes on inflamed skin.
  • Not drinking enough Dehydration is why people feel unwell after a day in the sun.

What helps

  • Sunscreen daily on healing skin Stops dark patches deepening and lasting for months.

How These Treatments Work

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Treatments for Sunburn do not all work in the same place. Tap one to see where it acts.

Pick a treatment
Skin basics
BARRIEREPIDERMISDERMISBLOOD VESSELSTAKES THE HEAT OUTSETTLES THE SURFACEQUIETS THE ALARMSTOPS THE NEXT ONE

The redness and heat are widened vessels. Cooling them settles both for a few hours at a time.

It does not speed up the repair, but it makes the days of tightness and peeling far more comfortable.

The pain and swelling come from inflammatory signals. Taken early, this turns them down.

Nothing undoes the DNA damage already done. Keeping more light off the skin is the only part of this you control.

The outer film of dead cells and oil. It holds water in and keeps irritants out, and it is thinner than a sheet of paper. Almost every dry, itchy, stinging skin problem starts here.

The outer layer, and the only one anything in a jar reaches. It renews itself constantly: a cell made at the bottom takes about a month to reach the surface and flake off. Most of what a skincare product does, it does here.

The living layer underneath, holding the blood vessels, the nerves and the collagen. It is where lasting change happens and it is hard to reach: most of what is sold for the skin never gets this far.

Over-the-Counter Products

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Everything here you can buy without seeing anyone.

Broad-spectrum sunscreen
Broad-spectrum sunscreen
Always
The only item on this page that acts before the injury rather than after it. SPF 30 or higher, broad spectrum, a teaspoon for the face and neck and about two tablespoons for the body, reapplied every two hours and after swimming or sweating. Quantity and reapplication matter far more than the number on the bottle. Once you are burnt it does nothing for the burn, but it still protects healing skin from marking.
Ibuprofen or naproxen
Ibuprofen or naproxen
Moderate evidence
An anti-inflammatory painkiller works on the actual mechanism of a sunburn, which is inflammation, and it helps most when it is started in the first few hours rather than added on day two. Take it regularly for the first day or so rather than only when the pain peaks. If you are pregnant or breastfeeding, ask the doctor managing your pregnancy which pain relief is appropriate.
Cool compresses and cool showers
Cool compresses and cool showers
Moderate evidence
The single most effective thing for pain in the first day, and it costs nothing. Cool, not cold, and never ice directly on burnt skin, which can deepen the injury. Ten or fifteen minutes at a time, repeated as often as it helps, and pat dry rather than rub. It relieves the pain without shortening the burn, which is true of everything in this section.
A fragrance-free moisturizer
A fragrance-free moisturizer
Moderate evidence
Applied while the skin is still slightly damp, a plain moisturizer eases the tightness and later reduces the itching and cracking that come with peeling. Fragrance-free matters, because inflamed skin reacts to things it would normally tolerate. It does not stop the peeling, since that is dead skin being shed after a real injury, but it makes the week considerably more comfortable.
Five aloe vera gel products lined up on white: squeeze bottles, a pump bottle and a jar16:9 hero for Aloe Vera. Never cropped: the tone strip and the corner logo depend on the full frame.
Limited evidence
Cooling and pleasant on a burn, and it is what most people reach for first. The trial evidence that it does anything beyond that is thin. Keep it in the fridge if you like it, choose a plain gel without added fragrance or alcohol, and do not expect it to shorten anything. It is comfort, not treatment.
A plain white ointment tube lying on its side, labeled Hydrocortisone with a blue swoosh16:9 hero for Hydrocortisone. Never cropped: the tone strip and the corner logo depend on the full frame.
Limited evidence
One percent hydrocortisone can take the edge off a small, sore area for a few days. Use it on unbroken skin only, never on blisters or open areas, and not over large parts of the body. It is a mild help rather than a fix, and if the burn is big enough that you want to cover it all, that is a burn worth having looked at.
Four ointments on white: CeraVe Healing Ointment, a Vaseline jar, a petroleum jelly tube and Aquaphor16:9 hero for Petrolatum. Never cropped: the tone strip and the corner logo depend on the full frame.
Limited evidence
Its job here comes later, on peeling skin and on any blister that has opened, where it stops the new skin drying and cracking and reduces the itch. Use it under a loose non-stick dressing rather than an adhesive one. It is not for the first day on an intact, hot burn, where a thick greasy layer traps heat and makes things feel worse.
Numbing sprays and gels
Numbing sprays and gels
Weak evidence
Benzocaine and lidocaine sprays sold for sunburn cause allergic rashes on inflamed skin often enough that they are not worth using. The relief is short, and an allergic reaction on top of a burn is a considerably worse week. Cool compresses and an anti-inflammatory painkiller do the same job without that risk.

Prescriptions

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These need a prescription.

16:9 hero for Mometasone. Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Mometasone works in the skin
Limited evidence
A stronger steroid cream, sometimes prescribed for a few days on a severe burn that hydrocortisone has not touched. It reduces the inflammation and the soreness a little. It does not change how long the burn lasts or repair any of the damage underneath, and it goes on unbroken skin only, never on blisters or open areas.
16:9 hero for Mupirocin. Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Mupirocin works in the skin
Limited evidence
An antibiotic ointment for the specific situation where broken blisters have become infected, which shows as increasing redness, swelling, heat or pus. It is not for a plain burn and does nothing for one. If the infection is spreading beyond the burnt area, antibiotic tablets are needed instead.

Procedures

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These are done in the office, usually over several visits.

No procedures listed yet.

When to See a Dermatologist

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Most sunburns are managed at home, but a large burn can make you genuinely unwell. Get medical care the same day for extensive blistering, fever with chills, severe headache, confusion, dizziness or fainting, vomiting, a very fast heartbeat, or dehydration with little or dark urine and intense thirst - and the same day for any sunburn in a baby under one year old. Book if the pain is not controlled at home, if a burned area becomes more red, swollen or hot or starts oozing pus, if blisters cover a large area or are on the face, if the burn is not improving after about a week, or if your eyes are painful, gritty or light-sensitive after intense sun or snow. Ask a doctor or pharmacist if you burned after very little sun, especially after starting a new medicine - the answer is a sun-protection plan, not stopping the medicine on your own.

— Dr. Schwarz, Board Certified Dermatologist

Complications

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Blisters that get infected

A blister means the injury went deeper into the skin. An intact blister is a sterile cover over an open wound, and popping one lets bacteria in and can turn a burn that would have healed cleanly into one that scars. Leave them alone. If one opens by itself, keep it clean, use plain petrolatum and a non-stick dressing, and get it looked at if the area becomes hot, swollen or starts oozing pus.

Heat illness and dehydration

A large burn is not only a skin problem. Fever, chills, headache, nausea, weakness, dizziness and intense thirst come from a big area of inflamed skin losing fluid alongside hours in the heat. It is often called sun poisoning, which it is not. Children and older adults reach this point sooner. It needs shade, fluids and, if there is confusion, fainting, vomiting or very little urine, same-day medical care.

Skin cancer decades later

This is the complication that never looks like one at the time. Repeated blistering sunburns, particularly in childhood and adolescence, are associated with a substantially higher risk of melanoma later, and ordinary cumulative exposure drives most other skin cancers. No amount of aftercare undoes it. It is why a pattern of burning every summer is worth a conversation, and why a history of repeated burns is a reason to arrange a skin check.

Lookalikes

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Contact Dermatitis

Plant sap on skin that then meets sunlight burns far harder than the sun alone, and lime juice is the classic culprit. It looks like sunburn except for the shape: streaks, drips, splashes and handprints, in odd angular patterns, on skin that was in no more sun than the skin beside it. It also leaves dark marks along the same lines for months afterwards.

Rosacea

Redness across the cheeks and nose after a hot day outdoors gets read as a mild facial sunburn, especially the first few times. Rosacea sits on the central face and spares the forehead edges, jaw and ears that a real burn would catch, it comes back again and again from heat, exercise, alcohol and stress rather than once from an afternoon, and small visible blood vessels are usually there when you look closely.

Cellulitis

A hot, red, tender, swollen area can look like a bad local burn, and people who spent the day outdoors often assume it is one. Cellulitis is on one limb only rather than on everything the sun reached, it has no sharp clothing line, it spreads outward over hours to days instead of settling, and it usually comes with fever and feeling unwell. It needs antibiotics, so the distinction matters.

Myths

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  • "You cannot burn on a cloudy day." A large share of ultraviolet light passes straight through light cloud. What cloud removes is the heat - the cue most people use to decide they have had enough.
  • "A base tan protects you." A tan gives very little protection, far below any sunscreen, and it is itself evidence of DNA damage. Getting burned in advance to avoid getting burned later is not a strategy.
  • "People with deeper skin tones do not burn." They do. More melanin means it takes longer, not that it cannot happen, and these burns are often missed because they are not red.
  • "You cannot burn through a window." Ordinary glass blocks most UVB, so a classic burn is unlikely. UVA passes through and still damages skin - long-term drivers show more damage on the side nearer the window.
  • "Peeling means it is healing, so no harm was done." Peeling is dead skin shed after a real injury. The visible part resolves; the DNA damage that raises skin cancer risk does not.
  • "Sunscreen will leave me short of vitamin D." Sunscreen in real-world use has not been shown to cause vitamin D deficiency, partly because nobody applies it thoroughly enough. If you are worried about your levels, get a blood test, not a sunburn.
  • "Put butter, ice or vinegar on it." Ice directly on burned skin can worsen the injury, and greasy kitchen remedies trap heat. Cool water, a light moisturizer and time are what help.
  • "Only bad, blistering burns count." They matter most, but the lifetime ultraviolet total drives most non-melanoma skin cancers, and much of that is ordinary exposure rather than dramatic burns.
  • "A higher SPF means I can stay out much longer." SPF numbers rise steeply for small gains; no sunscreen blocks everything. Quantity and reapplication matter far more than the number.

Questions Patients Ask

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How long does a sunburn last?

Redness appears within two to six hours, peaks around twelve to twenty-four hours, and settles over three to seven days, with peeling toward the end. Blistering burns take longer and can leave marks for months. Nothing shortens it.

Can I stop it peeling?

Not really. Peeling is dead skin being shed; the damage is already done. Moisturizer reduces itching and cracking. Do not pull the flakes off - that exposes tender new skin.

Should I pop the blisters?

No. An intact blister is a sterile cover over an open wound and lowers the risk of infection and scarring. If one opens, keep it clean, use plain petrolatum and a non-stick dressing, and have it checked if the area becomes hot, swollen or oozes pus.

Does one bad sunburn really raise my skin cancer risk?

Each burn adds to a lifetime total rather than deciding anything on its own. Repeated blistering sunburns, particularly in childhood and adolescence, carry a substantially higher risk of melanoma. Ordinary cumulative exposure drives most other skin cancers.

Why did I burn so badly when I was barely in the sun?

Usually a medicine that increases sensitivity to ultraviolet light - some antibiotics, diuretics, anti-inflammatories, retinoids and others. Plant sap, especially lime juice, does the same in streaks, and recent peels or laser lower the threshold. Ask a pharmacist rather than stopping any prescribed medicine yourself.

Is a tan from a tanning bed safer than one from the sun?

No. A tanning bed delivers a concentrated dose of ultraviolet light and causes the same DNA damage. Using one before the age of 35 carries a notably higher risk of melanoma. The tan is the injury response, so no version of deliberate tanning avoids it.

References

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