The warnings

The general warning duty

Updated October 2026

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What it says Which makes it a judgment Bath products have obvious candidates Slip is the one most often missed Essential oils are the second The Commissioner can prescribe more Write the warnings you believe in References

Above the two specific rules sits a general duty with no list attached.

What it says

The label of a cosmetic product shall bear a warning statement whenever necessary or appropriate to prevent a health hazard that may be associated with the product. No enumerated triggers, no thresholds.

Which makes it a judgment

And the judgment is yours, informed by the safety substantiation you were already required to do. The two rules work together: the substantiation tells you what the hazards are and this one asks you to warn about them.

Bath products have obvious candidates

A slippery tub from an oil, essential oils on sensitive skin, a hot shower steamer being handled, a product not intended for use on broken skin. None of those has a prescribed sentence and all of them are plausible warnings.

Slip is the one most often missed

A bath oil or a milk bath leaves a tub slick, and that is a fall risk for exactly the people most likely to use a long soak. A line about it is appropriate and costs nothing.

Essential oils are the second

Loading, sensitization and photosensitivity for citrus oils are real, and a bath distributes the oil over the whole body in warm water. That is a higher exposure than a leave-on product at the same percentage.

The Commissioner can prescribe more

The regulation provides for proposing new warnings, on the Commissioner’s initiative or on a petition with an adequate factual basis. So the list of specific cosmetic warnings is not closed.

Write the warnings you believe in

A warning that reflects a hazard you identified reads as considered. A page of borrowed boilerplate reads as borrowed, and it does not discharge a duty framed around your product.

References

21 CFR 740.1, which requires the label of a cosmetic product to bear a warning statement whenever necessary or appropriate to prevent a health hazard that may be associated with the product. law.cornell.edu

21 CFR 740.10, which requires each ingredient and each finished cosmetic product to be adequately substantiated for safety prior to marketing, and makes an unsubstantiated ingredient or product misbranded unless it bears the conspicuous statement "Warning - The safety of this product has not been determined" on the principal display panel. law.cornell.edu

21 CFR 740.17, Foaming detergent bath products, which defines such a product as anything intended to be added to a bath to produce foam that contains a surface-active agent serving as a detergent or foaming ingredient, and requires a prescribed caution and adequate directions for safe use except for products labeled as intended for use exclusively by adults. law.cornell.edu

Written from federal regulation, not from a formulation bench. Substantiating the safety of a cosmetic is a real body of work and nothing here is a substitute for it. Whether a particular product is a foaming detergent bath product within 21 CFR 740.17 turns on what it is and what it is intended for.