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The inner leaf gel is around 99% water, with polysaccharides — chiefly acemannan — plus amino acids, enzymes, sterols and salicylates.

The effects that hold up:

• Cooling. Evaporation from a high-water gel cools the skin, and on a sunburn that is most of the immediate relief.
• Hydration and film-forming. The polysaccharides hold water at the surface and form a light protective film.
• Anti-inflammatory activity, attributed to the sterols and salicylates, with reasonable supporting evidence for reduced erythema.
• Some evidence for accelerated healing of superficial and partial-thickness burns, from a body of small trials that is suggestive rather than conclusive.

What it is not is a treatment for the underlying damage. Sunburn is a DNA-damage event and nothing applied afterwards undoes it — see After-Sun Lotion.

This is the practical heart of the page. Products sold as "aloe vera gel" vary enormously, and independent testing has repeatedly found bottles containing little or no detectable aloe.

What to look for:

• Aloe first on the list, as Aloe barbadensis leaf juice — not water first with aloe near the preservatives.
• No added colour. Aloe gel is naturally clear to pale yellow-brown. The bright green ones are dyed, and green dye on a sunburn adds nothing.
• Minimal fragrance and alcohol. Alcohol-containing gels sting and dry, which is the opposite of the point.
• A thickener is normal — carrageenan, xanthan gum — because pure aloe juice is watery. Some products are largely thickener with a trace of aloe.

Between the leaf's rind and the inner gel is a bitter yellow latex containing anthraquinones — aloin and its relatives — which are potent stimulant laxatives. Properly processed cosmetic aloe is decolourised to remove them.

Two consequences:

• Oral aloe latex was removed from US OTC laxative products by FDA for lack of demonstrated safety and effectiveness data.
• Cutting a leaf at home produces gel contaminated with latex unless the leaf is stood upright to drain and the gel is carefully separated. Home-cut aloe also carries no preservative and spoils within days.

Cool the skin first, then apply generously and often. Refrigerating it is worth doing — much of the relief is temperature. Reapply as it dries; a dried aloe film flakes and does nothing.

Not on blistered or broken skin without medical advice, and not on a burn that is extensive, blistering, or accompanied by fever, chills or dizziness — those need a doctor.

Aloe is in the lily family; contact allergy is uncommon but real, and anyone with a lily or garlic-family allergy should patch test.

Cosmetic in the US — FDA primary category (15) suntan preparations, overlapping with (14) skin care — for a gel making soothing and moisturising claims. No premarket approval.

A claim to treat burns or wounds would be a drug claim, and aloe is not an approved active in the OTC skin protectant monograph — so a product claiming to heal is making an unapproved drug claim. "Soothes and cools sun-exposed skin" is cosmetic.

In the EU, preservatives come from the Annex V closed positive list of 60 entries, and Annex II prohibits 1,766 substances. The Common Criteria require cosmetic claims to be supported by verifiable evidence.

6–12 months after opening. A 99%-water product is a demanding preservation case, and it is often stored badly — in a beach bag, in the sun.

Discard at cloudiness, separation, a sour smell or any colour change. Fresh home-cut aloe keeps a few days refrigerated and no longer, and it has no preservative system at all.

• 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 — After-Sun Lotion.
• Barrier Cream — where the skin protectant monograph is dealt with in full.
• Regulatory statements here follow the FDA and EU sources listed on Cosmetics, read 16 August 2026.