Toxicity of B vits is very individual. You will have to experiment. If you find you get too much of a jolt from yours you might try a slow release version, so your system won't be so up and down with the "charge" of Bs.
As an example of individuality here... some people do well on 100 mg. of the Bs in a complex, then there's me... I take 12.5 mg. and I have to take them all separately, not in a complex. If I take a stronger complex my adrenals go crazy and I'm a real jittery nut case. Or I take a liquid B complex that has anywhere from 1-5 mg. of the different Bs.
I'd suggest you start with a lower one, such as 25 mg. of the different Bs.
Good luck Dave Oh, BTW... The symptoms of toxicity are the same as the deficiency symptoms.