B-complex may contain B6 - so too much of that is a bad thing..........
Found this online:

"-----------Vitamin B6 Overdose

People taking large dosages of vitamin B6 (pyridoxine) on a regular basis for an extended period of time should be aware that problems can arise. There is a potential for damage to your nerves, but in most cases it is reversible.

Symptoms that you will notice first with a vitamin B6 overdose are numbness and tingling in the hands and feet.

You may also notice a loss of manual dexterity and your balance may be a bit wobbly.--------------"

Liz