Does electronic cigarette "juice" need to be kosher (require a hechsher)? Does it matter what flavor the juice is?
According to the CRC-Chicago it needs a Hashgacha
Does the juice or flavor for electronic cigarettes pose kashrus issues?
Yes. Electronic cigarettes convert a specially formulated liquid into a vapor which the person inhales in a manner that mimics the way one inhales from a traditional cigarette. The liquid (which is sometimes called “juice”, “smoke-juice” or similar names) typically includes kosher-sensitive ingredients such as glycerin and flavors, and since the person imbibes the liquid/vapor, Rav Schwartz said that the liquid must be certified as kosher. We contacted a number of manufacturers who claim to use only kosher raw materials but there is no independent agency who certifies that claim, and therefore we are unable to recommend those products. [As with all medical issues, one should consult with their doctor before deciding to use or not use electronic cigarettes.]
They are different opinions, CRC holds that you need a Hechsher but they certify www.dropsmoke.com juices, they are other Rabbonim who hold that you don't need a Hechsher.