"Natural is gentler"

The claim

Plant-derived ingredients are inherently kinder to skin than synthetic ones.

What the evidence actually shows

The patch-test data invert the assumption.

The North American Contact Dermatitis Group analysed 24,246 patch-tested patients across 2007 to 2016 and found 5,504 — 22.7% — had fragrance or botanical allergy. The leading allergens were fragrance mix I at 10.6%, Myroxylon pereirae (balsam of Peru) at 8%, and fragrance mix II at 4.9%, with rising trends for fragrance mix I and II, cinnamic aldehyde and Compositae mix.

On essential oils specifically, a review in Dermatitis documents that nearly 80 essential oils have caused contact allergy, and that of 55 tested in consecutive patients with suspected dermatitis, nine produced more than 2% positive reactions: laurel, turpentine, orange, tea tree, citronella, ylang-ylang, sandalwood, clove and costus root. A multicentre French study confirms essential oils in consumer products cause allergic contact dermatitis and are routinely under-reported by patients.

There is a reason this is not surprising. Plants synthesise secondary metabolites as chemical defences — that is what they are for. Biological activity and irritancy are related properties, not opposites.

The honest version of the natural argument

There are genuinely good reasons to prefer some naturally derived ingredients: biodegradability, residue profile, sourcing, effects on non-target organisms, and in some cases better-characterised long-term use. Those are real arguments and they are the ones worth making.

"Gentler on skin" is not among them, and a brand making that specific claim is making the one natural-products claim the dermatology literature contradicts most directly.

What to do instead

Judge tolerability by patch testing and by ingredient, not by origin. If you have reactive skin, fragrance-free — which is a meaningful designation — is a better filter than "natural", which is not.