vegetable glycerin as a shampoo?

I was about to wash my hair and realized I am almost out of shampoo and since I order it and therefore have to wait a few days for it to arrive, I decided to try using the vegetable glycerin soap I use on my skin. As far as I know it is pure vegetable glycerin with no additives in a solid bar form. I just ran the bar over my hair as I would my skin and then worked the soap into a fine lather and rinsed. The soap actually
worked very well but I was wondering if it is ok to keep using it. Could vegetable glycerin damage hair or irritate the scalp?