I took burdock internally for a while but couldn't continue for very long. It would make me dizzy and give me headaches. So I didn't use it long enough to see any affect on my acne.
I don't think burdock should be taken without the supervision of a doctor. It's a strong herb. Thankfully, I wasn't taking any medications at the time, otherwise I'm sure it would have interacted with those and caused more side effects.