CHICAGO - Young people are increasingly abusing a drug found in nonprescription cough medicines that can produce hallucinogenic effects, but at a risk to their well-being, researchers said Monday.

Calls for help to California's poison control system and around the United States rose by roughly 50 percent each year between 1999 and 2004 for reactions to the drug dextromethorphan, a cough suppressant. It's found in cough medicines by brands including Pertussin, Robitussin, Benylin, Sucrets, Trocal, Vicks 44, Delsym, Diabe-TUSS, Cough X and Creo-Terpin.

Most of the calls involved side effects suffered by youths aged 9 to 17 years that included rapid heartbeat, high blood pressure, agitation, loss of muscle control and psychotic reactions, according to the report published in the Archives of Pediatrics and Adolescent Medicine.

Web sites that offer instructions on how to abuse legal medications have proliferated and many cough medicines containing the drug are available on the shelves of retail outlets and kept in the home, the report said.

"Preventive measures, such as placing detromethorphan-containing products behind pharmacy counters, may be an effective action to limit this increasing trend of abuse in adolescents," study author Jodi Bryner of the University of California, San Francisco, said.