I have good news for you if you like Monster Energy Drinks.
I contacted them asking about whether or not their main energy drink (this is only concerning the original/classic version) was vegan, and they said this:
Thank you for visiting the Monster Energy Website.
We use no animal bi-products in any of our products line. However, they are not vegan certified.
I contacted them because while the ingredients list (shown below) seems vegan, there’s a few of them that can come from either synthetic (vegan) or non-vegan sources:
The ingredients include carbonated water, sucrose, glucose, citric acid, natural flavors, taurine, sodium citrate, color added, panax ginseng root extract, L-carnitine, caffeine, sorbic acid, benzoic acid, niacinamide, sodium chloride, Glycine max glucuronolactone, inositol, guarana seed extract, pyridoxine hydrochloride, sucralose, riboflavin, maltodextrin, and cyanocobalamin.
Luckily, it turns out the Monster Energy drinks are vegan, so there’s one way to raise energy levels if needed. Not healthy, but vegan!
Note that other flavors, like Ultra Red have E120 (or cochineal), which is made from insects and isn’t vegan. Only the original Monster Energy is vegan, I haven’t looked at all of the other ones.