A second-degree sunburn is a burn that damages not just the outer layer of skin (the epidermis) but also part of the deeper layer underneath (the dermis). The hallmark sign is blisters. If your sunburn has blistered, turned deep red or dark, and the skin looks shiny or moist, you’re dealing with a second-degree burn rather than the more common first-degree sunburn that only causes redness and peeling.
How It Looks and Feels
A regular sunburn turns your skin pink or red and feels tender. A second-degree sunburn goes further. The skin takes on a shiny, wet-looking texture, and you’ll notice fluid-filled blisters forming within hours or the next day. Skin color ranges from deep red to dark brown depending on your skin tone and the severity. Swelling is common, and layers of skin may begin peeling away as the burn progresses.
Pain is often intense, especially with shallower second-degree burns. That might sound counterintuitive, but the nerve endings in the upper dermis are exposed and highly irritated. Deeper second-degree burns that reach further into the dermis can actually feel less painful because those nerve endings sustain more damage. So if a blistered area suddenly feels numb rather than agonizing, that’s not necessarily a good sign. It may mean the burn is deeper than it appears.
Superficial vs. Deep Second-Degree Burns
Not all second-degree sunburns are the same. Doctors distinguish between superficial and deep varieties, and the difference matters for healing and scarring.
A superficial second-degree burn damages the epidermis and only the upper portion of the dermis. The wound base looks moist and red, blisters are prominent, and it hurts significantly. These typically heal in under two weeks and generally leave no scar.
A deep second-degree burn reaches into the middle or lower dermis. The skin may show a mix of red and white patches, and blisters might be present but less uniform. Pain may be reduced or absent. These burns take two to three weeks or longer to heal, and scarring becomes much more likely. Burns that extend into the deepest part of the dermis carry a 70 to 80 percent chance of scarring. As a general rule, any burn wound that takes longer than 21 days to heal has a high likelihood of producing raised, thickened scars.
Healing Timeline
Most second-degree sunburns fall on the superficial end, since UV radiation typically doesn’t penetrate as deeply as a contact burn from a hot surface would. You can expect the worst of the pain and swelling to peak around 24 to 48 hours after sun exposure. Blisters may continue forming during this window.
If the burn is superficial, new skin grows back from structures in the upper dermis, and you’re looking at roughly one to two weeks of healing. The blisters dry out, the dead skin peels, and fresh pink skin appears underneath. That new skin will be sensitive to sunlight for weeks or even months, and temporary discoloration (lighter or darker patches) is common.
Deeper burns follow a slower path. The two-to-three-week range is typical for moderate depth, but burns reaching the deepest dermis can drag on beyond three weeks and may need medical intervention to heal properly. During this extended healing period, the risk of infection rises and the chance of permanent scarring increases substantially.
What to Do Immediately
Cool the skin with lukewarm (not ice-cold) water or cool compresses. Ice and ice water can further damage burned tissue. Get out of the sun and stay out. Drink extra fluids, because sunburns pull fluid toward the skin surface and can contribute to dehydration.
Leave blisters intact. They act as a natural sterile bandage over the damaged skin underneath. Popping them opens the door to bacteria and slows healing. If a blister breaks on its own, gently clean the area and keep it loosely covered. Over-the-counter pain relievers can help manage discomfort, and pure aloe vera gel (without alcohol or fragrance) can soothe the surface. Avoid petroleum-based products, which trap heat in the skin.
Keep the burned area clean and loosely covered with a non-stick bandage if clothing rubs against it. Watch for changes over the following days.
Signs That Need Medical Attention
Most superficial second-degree sunburns heal on their own with basic care. But certain situations call for professional help. Seek medical care if you develop large blisters, or if blisters form on your face, hands, or genitals, where scarring and functional problems are bigger concerns.
Infection is the main complication to watch for. Warning signs include blisters that fill with pus instead of clear fluid, red streaks spreading outward from the burn, increasing swelling, or worsening pain after the first couple of days rather than gradual improvement. A fever over 103°F (39.4°C) with vomiting, confusion, cold or clammy skin, dizziness, or faintness all warrant immediate medical attention, as these can signal a systemic response to severe burns or sun poisoning.
Long-Term Skin Effects
Superficial second-degree sunburns usually resolve without visible scarring, though the affected skin may look slightly different in color for several months. Deeper burns are more likely to leave lasting marks, ranging from flat discoloration to raised or textured scars.
Beyond cosmetic concerns, blistering sunburns carry a meaningful impact on skin cancer risk, particularly when they occur in childhood. A genetic analysis published in Environmental Science and Pollution Research found that childhood sunburns were associated with roughly four to five times the risk of developing melanoma. The risk for early-stage melanoma was even more pronounced, with up to a seven-fold increase on the trunk and an 18-fold increase on the face. These numbers reflect a causal relationship between UV damage during formative years and cancer development later in life, not just a correlation.
Even a single blistering sunburn in adulthood adds to your cumulative UV damage. After healing from a second-degree sunburn, protecting that skin from further UV exposure is essential. The new skin forming underneath is especially vulnerable, and re-burning the same area compounds the damage at a cellular level.