"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 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.