FDA requires coal tar hair dyes to bear a specific caution statement warning that the product may cause skin irritation and directing consumers to perform a patch test before use. This requirement applies regardless of origin. Imported coal tar hair dye products that lack the required caution statement are considered misbranded and may be refused entry at the port. Importers should verify labeling compliance before shipment.

The HTS applies the general rule of classification by principal function. A product primarily designed to cleanse hair belongs under 330510 (shampoos), even if it contains conditioning agents. A product primarily designed to permanently restructure hair belongs under 330520. Products whose primary function is conditioning, styling, coloring, or general hair care — and that do not fit a more specific heading — fall into the residual 330590 category. When a product genuinely performs multiple functions equally, GRI 3(c) and consultation with a licensed customs broker are appropriate.