Sunburn
Sunburn — skin damage caused by overexposure to ultraviolet radiation, resulting in redness, warmth, pain, and sometimes swelling or blistering. It is an inflammatory response that reflects injury to skin cells and DNA from UV light. Beyond short-term discomfort, repeated sunburns increase the long-term risk of premature aging and skin cancer.
Key points
- Sunburn is caused primarily by UVB radiation damaging skin cells, triggering inflammation and redness.
- Symptoms may appear within hours and peak around 12 to 24 hours after exposure.
- Cool compresses, gentle moisturizers, and hydration can ease discomfort while the skin heals.
- Broad-spectrum sunscreen, protective clothing, and shade are key to preventing sunburn and cumulative UV damage.
Aftercare: what helps, and what it cannot do
| What helps | Why it works | How long to judge |
|---|---|---|
| Getting out of UV entirely | Stops further injury to inflamed skin | Immediately, and until it settles |
| Cool compresses or a cool shower | Draws heat out; eases burning without shortening it | Minutes of relief; repeat over 24–48 hours |
| Bland fragrance-free emollient | Replaces water lost through a leaking barrier | Comfort within minutes; two or three times daily |
| Extra fluids | A large burnt area loses meaningful water | First 24–48 hours |
| Leaving blisters intact | A sterile cover; opening it invites infection | Several days, until they settle |
| Broad-spectrum sunscreen once healed | Prevents the next burn; nothing undoes this one | An ongoing habit, not a treatment |
What is actually happening in sunburnt skin
UVB is absorbed directly by DNA in epidermal keratinocytes, fusing adjacent pyrimidine bases into cyclobutane pyrimidine dimers. Where the damage load exceeds what repair enzymes can correct, the cell destroys itself rather than divide with corrupted instructions — the apoptotic keratinocytes known as sunburn cells. Inflammatory mediators separately dilate the dermal vessels, and that vasodilation, not the DNA damage, is the visible redness.
Because redness depends on that cascade rather than the exposure itself, it peaks 6 to 24 hours later, which is why people misjudge their dose. Peeling is sheet desquamation, layers of damaged keratinocytes shedding at once; whether you peel is a matter of degree, and the damage happened either way. The tan that follows is a delayed damage response, not recovery.
What aftercare can realistically achieve
Nothing available at home reverses the injury; aftercare manages symptoms while skin repairs itself. Cool compresses, a bland emollient, extra fluids and complete avoidance of further sun cover almost all of it. After-sun gels cool mainly through evaporation: real relief, not repair. Anaesthetic ingredients ending in -caine are better avoided on broken skin.
A mild burn usually fades over two or three days, peels around days four to seven, and settles within a fortnight. Deeper burns take longer and can leave a blotchier patch that, in richer skin tones, may take months to fade. Cumulative exposure matters more than any single episode: blistering sunburns, particularly in childhood, are associated with higher later melanoma risk.
When sunburn needs medical attention
Blistering over a large area, or on the face, hands or genitals, needs a clinician rather than aftercare. So does fever, chills, nausea, dizziness or confusion, which suggest heat illness rather than a skin problem and need urgent assessment. Severe pain, spreading redness or discharge from opened blisters warrants the same.
Sunburn in an infant or young child should always be reviewed by a clinician: thin skin, a large surface area relative to body size and limited fluid reserve change the risk entirely. Burning severely after little exposure is worth raising, since some medicines increase photosensitivity. A history of blistering sunburns is also reason to report any lesion that changes size, shape or colour, bleeds, or fails to heal.
Frequently asked
How can I soothe a sunburn at home?
Cool compresses, gentle fragrance-free moisturizers, staying hydrated, and avoiding further sun exposure can help ease discomfort as the skin recovers. Blistering, extensive, or severe burns should be evaluated by a healthcare professional.
Does a sunburn increase skin cancer risk?
Yes; repeated sunburns, especially blistering ones, are associated with a higher lifetime risk of skin cancers including melanoma. Consistent sun protection helps reduce this cumulative risk.
Why did my sunburn look worse the next morning?
Redness comes from an inflammatory cascade that takes hours to build, so it peaks 6 to 24 hours after exposure. What you see leaving the beach is not the finished result.
Does peeling mean the damage is being repaired?
Peeling is the shedding of keratinocytes damaged beyond repair, so it reflects how deep the injury went, not healing. Skin that never peels has still sustained DNA damage.
Can I use my usual retinoid or exfoliating acid while I am burnt?
Most people find it more comfortable to pause them: an impaired barrier makes actives sting and prolongs irritation. Anything prescribed is a question for the prescriber.
Does a base tan protect against sunburn?
Only marginally. A tan is itself a damage response, usually described as equivalent to a very low SPF — far less than most people assume.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
