Skin Care
How to Treat a Severe Sunburn: An Evidence-Based Timeline
The first 24 hours matter most. Cooling, hydrating, and pain management for moderate to severe sunburn — and when to go to an ER.
Sunburn is a delayed-onset burn injury. Redness peaks 12 to 24 hours after exposure, and inflammation continues for three to five days. What you do in the first hours meaningfully changes how bad the burn feels and how it heals.
The first hour
Get out of the sun. Cool the skin with a lukewarm shower or a cool damp towel — not ice, which can extend the injury. Take ibuprofen or naproxen immediately; NSAIDs blunt the prostaglandin cascade driving the burn and are most effective when taken early.
The first 24 hours
Hydrate aggressively — burned skin pulls fluid to the surface. Fragrance-free moisturizer with ceramides or aloe vera gel reduces discomfort. Avoid petroleum jelly, which traps heat. Skip retinoids, exfoliants, and waxing for at least a week.
Signs you need medical care
- Blistering over more than 20 percent of the body
- Fever, chills, or nausea
- Confusion or dizziness (possible heatstroke)
- Severe pain not managed by OTC medication
- Signs of infection: yellow discharge, expanding redness, red streaks
The healing window
Peeling starts around day three to seven. Do not pick — you can extend hyperpigmentation. Keep the area moisturized and out of the sun until fully healed, then use SPF 50 on the site for the next month because new skin sunburns fast.
Key takeaways
- Cool, hydrate, ibuprofen early.
- Blistering over 20 percent BSA or fever means ER.
- Protect healed skin from sun for a month afterward.