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UV radiation damages DNA in skin cells directly — forming cyclobutane pyrimidine dimers — and generates reactive oxygen species. The visible burn is the inflammatory response to that damage several hours later, which is why sunburn peaks 12 to 24 hours after exposure rather than immediately.

Some of the damage is repaired. Some is not, and unrepaired mutations accumulate. The tan that follows is itself evidence of DNA damage — melanin production is a defensive response to it.

So an after-sun lotion is symptom relief. That is a real and useful thing, and it is not a repair.

In order of usefulness:

1. Cool it. Cool showers, cool damp cloths. Not ice, which damages already-injured skin.
2. Hydrate internally. A burn draws fluid to the skin surface and away from the rest of the body.
3. Moisturise while damp, repeatedly. Emollients and humectants; nothing occlusive on a hot burn.
4. Oral anti-inflammatories — ibuprofen or aspirin — reduce pain and inflammation, and are more effective than anything topical.
5. Leave blisters alone. A blistering burn is a second-degree burn.
6. Cover it and stay out of the sun until healed.
7. See a doctor for extensive blistering, fever, chills, confusion or dizziness — those indicate sun poisoning or heat illness, and for a young child a significant burn is a medical matter.

• "Caine" anaesthetics — benzocaine, lidocaine in OTC burn sprays. They sting, they are a recognised sensitiser, and benzocaine carries a rare risk of methaemoglobinaemia, which FDA has warned about.
• Petroleum jelly and heavy occlusives on a fresh burn, which trap heat.
• Butter, oils and household remedies.
• Exfoliating or picking the peel. Peeling is the shedding of dead damaged cells; let it go on its own.
• Alcohol-heavy lotions and fragrance, on skin whose barrier has been destroyed.

Class	Doing what	Names
Humectant	Rehydration	Glycerin, panthenol, hyaluronic acid, urea
Anti-inflammatory	Redness and heat	Aloe vera, bisabolol, allantoin, oat, madecassoside, niacinamide
Emollient	Barrier repair	Ceramides, squalane, shea
Antioxidant	Mops up some reactive species	Vitamin E, vitamin C, green tea
Cooling	Comfort	Menthol — mild, and irritating on a bad burn

Fragrance-free is the right default on skin whose barrier has just been destroyed.

Cosmetic in the US — FDA primary category (15) suntan preparations, overlapping with (14) skin care — for a moisturising lotion with soothing and appearance claims.

It becomes an OTC drug with a skin protectant claim using a monograph active such as petrolatum, dimethicone or allantoin, or with an external analgesic active such as benzocaine or lidocaine — those carry a Drug Facts panel and an expiration date.

A claim to treat or heal sunburn would be a drug claim; "soothes skin after sun exposure" is cosmetic, which is why the wording is always careful.

In the EU, preservatives come from the Annex V closed positive list, and named fragrance allergens must be declared individually above 0.001% in leave-on products.

12 months after opening. A water-based emulsion in a bottle that spends its life in a beach bag is heat-cycled repeatedly, which stresses the preservative system and breaks emulsions.

Discard anything separated, thinned, discoloured or changed in smell — and do not carry a half-used bottle over to next summer from a bag that spent a season in the sun.

• Sun and Tanning — the shelf this sits on, and the rest of it.
• Cosmetics — what the label is legally allowed to say, and the full catalogue.
• The rest of After sun — Aloe Vera Gel.
• Sunscreen Lotion — the thing that would have prevented this.
• Health and Wellness — where severe burns belong.
• Regulatory statements here follow the FDA and EU sources listed on Cosmetics, read 16 August 2026.