Sun Poisoning: What to Do and When to Get Help

Sun poisoning is an informal term for a severe sunburn that goes beyond ordinary redness and tenderness, producing symptoms like blistering, swelling, nausea, fever, and chills. It is not a medical diagnosis you will find in a textbook but rather a widely used shorthand for a sunburn intense enough to make you feel systemically unwell. The line between a “bad sunburn” and “sun poisoning” is blurry, but the distinction matters because the worse end of the spectrum can require medical attention and carries real long-term consequences for your skin.

What Sun Poisoning Actually Means

Doctors do not use the phrase “sun poisoning” in clinical settings. What most people mean when they say it is a sunburn severe enough to produce whole-body symptoms on top of the usual redness and pain. A mild sunburn might leave you pink and sore for a day or two. Sun poisoning, by contrast, tends to involve large blisters, significant swelling, headache, fever, nausea, dizziness, or fatigue. The skin damage is deep enough that your body mounts an inflammatory response you can feel far from the burn itself.

At the cellular level, severe UV exposure triggers a wave of damage. Skin cells called keratinocytes absorb UVB radiation, and when DNA damage becomes irreparable, those cells undergo programmed death, a process researchers call the “sunburn cell” response.¹ At the same time, UVB triggers cell membranes to release fatty acids that get converted into inflammatory signaling molecules, ramping up redness, swelling, and pain over the hours after exposure.² This is why a sunburn typically worsens well after you have come inside: the inflammatory cascade is still building. In severe cases, the skin’s barrier function breaks down so much that water loss through the burned skin peaks around four days later, contributing to dehydration and that tight, swollen feeling.³

What to Do When You Have a Severe Sunburn

The first and most obvious step is to get out of the sun entirely and stay out for the rest of the day. From there, the goal is to reduce inflammation, manage pain, prevent dehydration, and protect the damaged skin while it heals. Most cases of sun poisoning can be managed at home, but the process takes patience because the burn typically gets worse before it gets better.

Cool the skin: Apply cool (not ice-cold) compresses or take a lukewarm bath. Avoid ice directly on the skin, which can further injure damaged tissue.
Hydrate aggressively: A severe sunburn pulls fluid into swollen tissue and increases water loss through the skin surface. Drink more water than feels necessary, and if you feel dizzy or lightheaded, add an electrolyte drink.
Take oral anti-inflammatories early: Ibuprofen or naproxen can blunt the inflammatory cascade that drives sunburn pain and swelling. UVB exposure induces a surge of COX-2 enzyme activity and prostaglandin release in the skin, which is exactly what these drugs target.⁴ Taking them as soon as you notice the burn is more effective than waiting until the pain peaks.
Moisturize gently: Aloe vera gel is one of the most studied topical options for burned skin. In a clinical trial comparing aloe vera gel to silver sulfadiazine cream on burn wounds, patients treated with aloe experienced faster healing, less pain over two weeks, and a significant reduction in itching.⁵ Plain, fragrance-free moisturizers also help. Avoid anything with alcohol, benzocaine, or lidocaine, which can irritate damaged skin or cause allergic reactions.
Leave blisters intact: If blisters form, resist the urge to pop them. The fluid inside cushions the healing skin beneath and acts as a natural barrier against infection. If a blister breaks on its own, gently clean the area and apply a thin layer of petroleum jelly and a loose bandage.

Do Topical Steroids Help

You might assume that a strong anti-inflammatory cream like a corticosteroid would be the obvious treatment, but the evidence here is surprisingly disappointing. A randomized double-blind trial found that applying moderate-potency or high-potency topical corticosteroids six or twenty-three hours after UV exposure did not provide a clinically useful decrease in the sunburn reaction.⁶ The only scenario where the effect was meaningful was when a high-potency steroid was applied thirty minutes before UV exposure, which is obviously not how sunburn treatment works in real life.

A separate trial found some benefit from twice-daily corticosteroid treatment starting after sunburn, with treated skin showing lower overall sunburn severity compared to untreated skin around days three through five.⁷ The difference was statistically significant but modest. In practice, this means that slathering on hydrocortisone cream the evening after a bad burn is unlikely to produce dramatic relief. You are better off relying on cool compresses, moisturizers, and oral NSAIDs as your main treatment strategy, and using a mild steroid cream if you have one on hand but not expecting it to be a game-changer.

When to See a Doctor

Most sunburns, even painful ones, heal without medical intervention within a week or two. But certain signs mean the burn has crossed into territory that needs professional help. Head to a doctor or urgent care if you experience any of the following:

Widespread blistering: If blisters cover a large area of your body (roughly a quarter of your trunk or more), the risk of infection and fluid loss increases significantly.
High fever or chills: A temperature above about 101°F (38.3°C) alongside a sunburn suggests your body is mounting a significant systemic inflammatory response, sometimes called “sun sickness.”
Signs of dehydration: Dark urine, dizziness when standing, rapid heartbeat, or confusion all point to fluid loss that may need IV replenishment.
Signs of infection: If burned skin develops increasing pain after the first two days, red streaks spreading away from the burn, pus, or warmth beyond the original burned area, infection may be setting in.
Sunburn in a young child or infant: Infant skin has a less developed barrier and is more vulnerable to damage, fluid loss, and absorption of any topical products.⁸ Any sunburn in a baby under one year old warrants a call to the pediatrician.

For severe cases that reach the emergency department, the cost of care is not trivial. A study analyzing over 82,000 sunburn-related ED visits in the United States found that the average visit cost about $1,130, with lower-income young adult men being the most likely demographic to end up there.⁹ That figure underscores a point worth remembering: catching a severe sunburn early and managing it aggressively at home, before symptoms spiral, is worth the effort.

Conditions That Look Like Sun Poisoning but Are Not

Not every painful rash that appears after sun exposure is a straightforward sunburn. Several other conditions can mimic sun poisoning, and treating them incorrectly can make things worse.

The most common imitator is polymorphic light eruption, often called “sun allergy.” It is the most common immune-mediated reaction to UV light, and it looks different from a sunburn: instead of uniform redness, you get itchy red bumps, patches, or small blisters, usually on areas that are not accustomed to sun exposure, like the chest or arms in early spring.¹⁰ It tends to improve as the season goes on and the skin gets gradually acclimated. If you notice you get a rash after your first warm-weather sun exposure each year but it fades after a few days and does not recur once you have had moderate exposure, this is a strong candidate.

Phytophotodermatitis is another one that catches people off guard. This happens when a photosensitizing compound from a plant contacts your skin and then the skin is exposed to sunlight. The classic culprits are limes, lemons, celery, wild parsnip, and figs.¹¹ The reaction often appears as bizarre streaks or handprint-shaped burns that do not match a typical sunburn pattern, because they follow exactly where the juice or sap dripped on the skin. The photosensitizing compounds involved belong to the coumarin and furocoumarin families found in these plants.¹² Making cocktails with fresh lime on a sunny patio is one of the most common triggers, which is why some dermatologists call it “margarita burn.”

Drug-induced photosensitivity is a third possibility. Certain medications, including common antibiotics like doxycycline, diuretics, some antidepressants, and retinoids, make the skin far more reactive to UV light. If you recently started a new medication and burn dramatically despite moderate sun exposure, the drug may be amplifying the damage. Check the prescribing information or ask your pharmacist.

Who Is Most Vulnerable

Anyone can get sun poisoning with enough UV exposure, but some people reach that threshold far more quickly. Skin pigmentation is the most obvious factor: lighter skin absorbs less UV before damage occurs. But the genetics go deeper than just visible skin tone. Variants in the melanocortin-1-receptor gene, which is best known for its link to red hair, play a significant role in determining sun sensitivity even in people who do not have red hair. Research in Irish and UK populations found a clear association between the number of MC1R variant alleles a person carries and their ability to tan after repeated sun exposure, suggesting that the gene directly controls the tanning-versus-burning balance.¹³ In other words, two people with similar-looking skin can have very different burn thresholds depending on their MC1R status.

Children deserve special mention. Infants and young children have thinner skin with a less mature barrier, which means UV penetrates more easily and the consequences of damage are more severe.⁸ Sunscreen is generally not recommended for babies under six months, which means physical shade and clothing are the only reliable protection for the youngest children.

Environmental Factors That Catch People Off Guard

Many of the worst sunburns happen not on a sweltering beach day but in environments where people underestimate UV exposure. Overcast skies block visible light more than UV, so you can burn on a cloudy day almost as easily as on a clear one. Water, sand, and concrete all reflect UV upward onto the face, neck, and underside of the arms, areas that get hit from both directions.

Mountain environments are among the sneakiest settings for severe burns. UV intensity increases with altitude because there is less atmosphere to filter it, aerosol levels tend to be lower, and snow is an extremely efficient UV reflector.¹⁴ Skiers and snowboarders routinely suffer sun poisoning on exposed skin, particularly around the nose, lips, and under the chin where reflected UV off the snow is intense. If you are at altitude and on snow, you need just as much or more sun protection as you would at a tropical beach.

Time of day matters, too. UV radiation peaks between roughly 10 a.m. and 4 p.m. in most locations. A common mistake is assuming that cooler temperatures or a breeze mean lower UV, when in reality those factors just mask the heat you feel from infrared radiation while doing nothing to reduce the UV that actually causes the burn.

The Long-Term Stakes of Severe Burns

Sun poisoning is acutely miserable, but the damage does not end when the peeling stops. The DNA mutations that accumulate from severe burns are permanent, and cumulative sunburn history is one of the strongest predictors of skin cancer later in life. A comprehensive meta-analysis found that the total number of lifetime sunburns is clearly important in melanoma risk, with the highest risk seen when sunburn frequency is measured across adult years and over a full lifetime.¹⁵

Blistering burns in adolescence appear to carry a particularly concentrated risk. A large cohort study found that people who experienced five or more blistering sunburns between ages fifteen and twenty had roughly 80% higher risk of melanoma, and about 68% higher risk of basal cell and squamous cell carcinoma, compared to those with no sunburns in that period.¹⁶ A Norwegian cohort study tracking women’s sunburn patterns over decades confirmed this, finding that those who maintained consistently high sunburn rates throughout life had about 50% greater risk of both melanoma and squamous cell carcinoma.¹⁷

These numbers do not mean a single bad sunburn guarantees cancer. They mean the risk accumulates meaningfully with each severe burn, and the burns you get when you are young seem to matter at least as much as those later in life. If you have already had several blistering burns, you cannot undo that damage, but you can change the trajectory going forward. Dermatologists generally recommend that anyone with a significant sunburn history get annual skin checks starting in their twenties or thirties rather than waiting for a suspicious mole to appear.

Sunburn Recovery Timeline

Knowing what to expect over the days following a severe sunburn can keep you from panicking or, conversely, from ignoring warning signs. A typical course looks like this:

Hours 0–6: Redness begins, often subtle at first. You may not realize how bad the burn is until the evening. This is when oral anti-inflammatories do the most good.
Hours 6–24: Pain and redness intensify. Swelling may start, especially on the face. This is often the most alarming phase because symptoms are still getting worse. Nausea, headache, or chills can appear if the burn is severe.
Days 2–4: Peak discomfort. Blisters may form. The skin barrier is at its most compromised, with water loss through the burned surface peaking around day four.³ Stay especially diligent about hydration during this window.
Days 5–7: Pain begins to ease. Peeling often starts as the dead outer layer of skin sheds. This is cosmetically annoying but is a sign of healing. Do not pull peeling skin off; let it come away naturally.
Days 7–14: Most first-degree burns (redness without blistering) are resolved. Blistered areas may take the full two weeks or longer. New skin underneath will be especially sensitive to UV, so avoid additional sun exposure on those areas.

If your symptoms are not trending toward improvement by day four or five, or if new symptoms like fever or spreading redness appear after the initial phase, see a doctor. A burn that is getting worse rather than better after the first forty-eight hours may be infected or may indicate a photosensitivity condition beyond an ordinary sunburn.

Preventing the Next Episode

If you have had one bout of sun poisoning, you know the misery well enough to want to avoid a repeat. Broad-spectrum sunscreen with at least SPF 30 is the most studied line of defense, but it only works if you apply enough of it and reapply every two hours or after swimming or sweating. Most people apply only about a quarter to half the amount used in the studies that generate SPF ratings, which means the protection you actually get is substantially less than the number on the bottle.

Physical barriers are even more reliable. A tightly woven long-sleeve shirt blocks UV far more consistently than sunscreen, and a wide-brimmed hat protects the ears, nose, and back of the neck, three of the most common spots for skin cancer. UV-protective clothing with a UPF rating takes the guesswork out of fabric choice. Seeking shade during peak UV hours, wearing sunglasses with UV protection, and being especially cautious in the high-risk environments discussed earlier round out a practical prevention strategy. None of this is complicated, but the pattern among people who get sun poisoning repeatedly is almost always one of underestimating conditions rather than lacking knowledge about sunscreen.

1
PubMed. The sunburn cell: regulation of death and survival of the keratinocyte
2
PubMed Central. The sunburn response in human skin is characterized by sequential eicosanoid profiles that may mediate its early and late phases
3
PubMed. Ultraviolet B-induced alterations of the skin barrier and epidermal calcium gradient
4
PubMed. Topical application of a selective cyclooxygenase inhibitor suppresses UVB mediated cutaneous inflammation
5
PubMed Central. A Comparative Study of the Impacts of Aloe vera Gel and Silver Sulfadiazine Cream 1% on Healing, Itching and Pain of Burn Wounds
6
PubMed. Topical corticosteroids in the treatment of acute sunburn
7
Clinical and Experimental Dermatology. A randomized, controlled study of the safety and efficacy of topical corticosteroid treatments of sunburn in healthy volunteers
8
PubMed Central. Skin Physiology of the Neonate and Infant: Clinical Implications
9
SpringerLink. Trends in emergency department visits due to sunburn and factors associated with severe sunburns in the United States
10
PubMed. Immunopathogenesis and management of polymorphic light eruption
11
PubMed Central. Lime-induced phytophotodermatitis
12
PubMed Central. A spotlight on lime: a review about adverse reactions and clinical manifestations due to Citrus aurantiifolia
13
The Lancet. Melanocortin-1-receptor variants and susceptibility to sunburn
14
Atmospheric Chemistry and Physics. Personal UV exposure in high albedo alpine sites
15
PubMed Central. Sunburns and risk of cutaneous melanoma, does age matter: a comprehensive meta-analysis
16
Cancer Epidemiology, Biomarkers & Prevention. Long-term Ultraviolet Flux, Other Potential Risk Factors, and Skin Cancer Risk: A Cohort Study
17
JAMA Dermatology. Lifetime Sunburn Trajectories and Associated Risks of Cutaneous Melanoma and Squamous Cell carcinoma Among a Cohort of Norwegian Women