Valium, a cheap and odourless drug, is making the rounds of a Nova Scotia high school, where the principal estimates two dozen students are abusing it.

At Millwood High School in Lower Sackville, Valium pills are called "blueberries" and sell for $2 each.

Student Jessica Haley said she has seen classmates high on Valium and has heard stories of students taking 70 pills in a weekend.

"They pretty much pop it like candy," she told CBC News on Wednesday.

"You can go pretty much anywhere around the school," said Ryan Martin, another student. "They'll offer it to you. You either take it or you don't."

With squinty eyes, slurred words and wobbly legs, a student on Valium can appear drunk, but there's no telltale odour.

Prescription drug abuse among teens is one of the fastest growing trends in the United States.

Valium and drugs like it are sometimes used in combination with alcohol, ecstasy or cocaine, which can be deadly.

Principal Lachie MacIntosh estimates about two dozen out of 660 students are abusing Valium, though he admits it's difficult to monitor and he doesn't know where the pills are coming from.

"As a principal, I'd never seen it before," MacIntosh said.

"I suspect and I'm quite confident it's not a phenomenon native to Millwood. It's a high school feature. My colleagues at other schools are dealing with it in their own way."

MacIntosh has been meeting with concerned parents and has suspended some students.

While the adults are just hearing about it, some students told CBC News that Valium abuse is old news.