By Lynne Adkins

PHILADELPHIA (CBS) - Generic prescription medication used to save shoppers money over named brands, but now that's not always the case.

You can get sticker shock at the local pharmacy trying to purchase a generic medication. John Williamson, Assistant Director of Pharmacy at Thomas Jefferson University Hospital says there are several reasons:

"It's just basic supply and demand for some things. In the past you could have four or five manufacturers of a single product, and that gets whittled down to one or two and they can charge whatever they want to."

Or a big company buys out the smaller generic maker and raises prices and some drug makers are not passing stringent federal regulations and that puts a squeeze on supply.

Still, Williamson says, overall, generics will save you cash.