The labeling requirements for skin care products in the U.S. would depend on whether the product is regulated as a cosmetic or a drug. The Fair Packaging and Labeling Act (FPLA), enacted in 1967, directs the Federal Trade Commission (FTC) and the Food and Drug Administration (FDA) to issue regulations requiring that all "consumer commodities" be labeled to disclose net contents, identity of commodity, and name and place of business of the product's manufacturer, packer, or distributor. The FPLA includes specifications on how the net quantity of contents should be listed in terms of weight, measure, or numerical count, and specifies that measurements must be in both metric and inch/pound units. FDA administers the FPLA with respect to foods, drugs, cosmetics, and medical devices. The regulation for the declaration of the net quantity of contents for cosmetic products in metric units is allowed as a supplemental statement, but not required (see Title 21, Code of Federal Regulations (CFR) part 701.13. Also, FDA has published a Cosmetic Labeling Manual. Over-the-counter (OTC) drug products are subject to a different set of labeling requirements that specify both content and format in great detail (see 21 CFR 201.66).

The use of the "e" in a net quantity statement is an approved format in labeling some products that require both metric and avoirdupois units. For example, "100 g e (3.5 oz)" is listed as an example of an approved statement of weight or mass in 16 CFR 500.8(a). Title 16, section 500 of the Code of Federal Regulations contains FPLA regulations for products regulated by FTC.