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• A thinner stratum corneum in newborns, maturing over the first year.
• Much higher surface area relative to body mass, so any absorbed substance is a proportionally larger exposure.
• A developing barrier and acid mantle, both disrupted more easily by surfactants.
• Higher transepidermal water loss in the first weeks.
• The vernix caseosa on a newborn is protective and should not be scrubbed off.

Formulation follows: amphoteric and non-ionic surfactants — cocamidopropyl betaine, coco-glucoside, decyl glucoside — at low concentration, at a pH close to the skin's own, fragrance-free where possible.

Plain water is sufficient for most of a baby's body, most of the time.

The general guidance from paediatric and dermatology bodies:

• Newborns need very few baths — two or three a week is ample, and daily bathing is unnecessary.
• Water alone is fine for a young infant; a mild cleanser can be used from the early weeks if wanted.
• The nappy area and any soiling need cleaning every time, obviously.
• Bath water warm, not hot, and short — five to ten minutes.
• Pat dry, do not rub, and moisturise immediately if the skin is at all dry.

For eczema-prone babies, the emollient matters more than the wash: bathing with a soap-free cleanser and applying a leave-on emollient straight afterwards is the established routine, and daily bathing with emollient is often recommended rather than avoided.

• True soap. Alkaline at pH 9 or above, and too stripping for infant skin. See Bar Soap.
• Fragrance, the leading avoidable irritant.
• Essential oils on infant skin — several are irritant or worse in young children.
• Antibacterial claims. FDA's 2016 rule banned nineteen ingredients, including triclosan, from consumer antiseptic washes, having found no demonstrated benefit over plain soap and water.
• Formaldehyde-releasing preservatives and isothiazolinones, worth avoiding specifically for this age group.

Cosmetic in the US — FDA primary category (01) baby products — and it bears repeating that there is no separate, stricter safety standard for children's cosmetics in the US, and no premarket approval.

What does apply: colour additives must be approved for the intended use; under MoCRA, facilities register, products are listed, safety substantiation records must be held, and serious adverse events are reportable within 15 business days.

In the EU, cosmetics intended for children under three require specific attention in the safety assessment under Regulation (EC) No 1223/2009 — a materially stronger requirement than anything in the US framework. Preservatives come from the Annex V closed positive list of 60 entries, and methylisothiazolinone is capped at 15 ppm in rinse-off products and prohibited in leave-on.

12 months after opening. Low-surfactant, high-water products with restrained preservative systems are a demanding case, and a bottle beside a bath is handled with wet hands constantly.

Discard at cloudiness, separation or an odour change. Never top it up with water.

• Baby — 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 Washing — Baby Shampoo · Baby Bubble Bath.
• Baby Lotion — the step that matters more than the wash.
• Regulatory statements here follow the FDA and EU sources listed on Cosmetics, read 16 August 2026.