Hi Hippo,
I have B complex 100mg (tweenlab), that means that all B group vitamins are 100mg.
My Biotin is from the company "NOW", they are the cheapest.
If you are taking the overdose of B5 one of the side effect is a hair loss, and that why you have to balance it with the rest of the supplement.
I don't think it is because of the C vitamin, but I am not an expert on this.
I did the Liver Flush without the Epsom Salt and it make it much easier, and also I have used grapefruit instead of lemon. Mixed that way makes it much easer to swallow.The nausea is common thing, but you can take peppermint candy right after drinking it, that will help the digestion.
For more info you can search the FAQ, liver section note. There are some good tips on how to do it.