Philadelphia officials are grappling with what they call the latest trend in teen substance abuse: ingesting legal drugs like dextromethorphan (DXM) purchased over the internet.

DXM–an ingredient in over-the-counter cough syrups–is easy to get but when misused can be just as deadly as any illegal substance, said Sgt. Philip Bueki, a Pennsylvania state Drug Abuse Resistance Education (DARE) coordinator.

In January, four Conestoga High School sophomores were hospitalized after ingesting DXM purchased through the internet by two classmates. The four, all girls, were treated and released.

While DXM doses found in cough syrup can alter the body’s chemistry to the point where people can get a buzz or feel light-headed, the drug has never been regulated because of its medicinal use. The average dose in Robitussin is about 10 mg, but people who abuse DXM might take up to 1,000 mg, authorities said.

A search on the internet produced more than a dozen sites devoted to DXM, including those that advertise the sale of the drug and others touting its effects and recommending music to listen to while taking it.

“This is a new area that needs to be addressed,” Mike Cullin, a Lower Merion, Pa., DARE officer told the Philadelphia Inquirer. “We’re realizing there needs to be a joint effort between the schools and the police to teach kids all we know about what is out there.”