http://www.fda.gov/downloads/tobaccoproducts/labeling/rulesregulationsguidance/ucm499354.pdf
3. What is a “covered tobacco product”? Covered tobacco product means any tobacco product deemed to be subject to the FD&C Act pursuant to § 1100.2 of this chapter (i.e., subchapter K), but excludes any component or part that is not made or derived from tobacco. Covered tobacco products include ENDS, cigars, pipes, waterpipe, dissolvable nicotine products, to name a few, as well as parts and components made or derived from tobacco, e.g., an e-cigarette cartridge containing e-liquid made or derived from tobacco.
For example:
• An e-liquid with nicotine is a covered tobacco product;
• An e-liquid without nicotine may be a component (and subject to FDA’s tobacco control authorities) if it is intended or reasonably expected to be used with or for the human consumption of a tobacco product and does not constitute a tobacco product accessory (e.g., with liquid nicotine); but
• An e-liquid that does not contain nicotine or tobacco or a tobacco derivative is not a covered tobacco product as defined by the Deeming Rule (§ 1140.3; 1143.1).
And:
http://www.fda.gov/downloads/tobaccoproducts/labeling/rulesregulationsguidance/ucm499352.pdf
E. E-liquids
For the purposes of this guidance document, liquid nicotine and nicotine-containing e-liquids (i.e., liquid nicotine combined with colorings, flavorings, and/or other ingredients) are generally referred to as e-liquids.
Liquids that do not contain nicotine or other material made or derived from tobacco, but that are intended or reasonably expected to be used with or for the human consumption of a tobacco product, may be components or parts and, therefore, subject to FDA’s tobacco control authorities.
F. Finished Tobacco Product
The term finished tobacco product refers to a tobacco product, including all components and parts,
sealed in final packaging intended for consumer use.
For example, an e-liquid sealed in final packaging that is to be sold or distributed to a consumer for use is a finished tobacco product, but in contrast, an e-liquid that is sold or distributed for further manufacturing into a finished ENDS product is not itself a finished tobacco product. At this time, FDA does not intend to enforce the premarket authorization requirements against e-liquids or other components and parts of newly deemed products that are not finished tobacco products. Finished tobacco products that are not covered tobacco products are not subject to the health warning statement requirements (21 CFR part 1143), age and identification restrictions (21 CFR 1140.14), and vending machine restrictions (21 CFR 1140.14) (see definition of covered tobacco product).