Is Zipfizz safe?

I recently bought some Zipfizz to use as a dietary supplement. It as 25000 mcg of Vitamin B12 plus about 16 other vitamins and minerals. When I first started taking it, I loved it for the extra energy and alertness. But quickly started having trouble sleeping through the night. Felt like I had super high levels of caffeine. This does list caffeine from guarana seed extract, Green Tea Leaf extract, Grape Seed extract, L-Taurine and Alpha-Lipoic.  Also started feeling "hyper" and had a mid-afternoon headache. I stopped taking the Zipfizz but would love to get a little of that boost back. Should I take smaller amounts or just give it up?  What about that massive does of B12? Can you overdose on B12?

[cirrus6000]

You cannot overdose on vitamin B12. this is because it is a water soluble vitamin as are all the B's and C. Any of it that you do not use just passes through you and is excreted via your urinary system.