There’s no mention of certification on their site, and one product uses a bovine derived ingredient (which possibly could make other product treif if produced on the same equipment).
I would definitely stay away from it without any further info. Contact the kashrus agencies. They might know more.
A quick Google search showed that the Star-K and OU both had a notice from 2008 about a kosher product which was packaged with a promotional package of EmergenC. They said the EmergenC is not kosher.
Yes if you look at the star-K website: Original Formula
Cranberry-Pomegranate, Raspberry, Lemon Lime, Pink Lemonade, Acai Berry, Coconut Pineapple, Strawberry Kiwi, Berry Blss, Meyer Lemon, Tropical