B-complex Vac while breastfeeding - is it safe?

To my knowledge it is safe, I had last year while I was breastfeeding my LG and suspected I was pregnant again, and the pharmacist said its ok.

He did say its worth it to come every week for a few weeks then every 10 days, then every 2nd week. And so on.

Thinking about it, it may do me some good right now, I am feeling quite run down.

I am returning to work in may, and i just want to get an energy boost. Is it safe to get a b.complex vac?

thanx!