High school seniors who use heroin also commonly use multiple other drugs, according to researchers at New York University. On average, these students use five other drugs, HealthDay reports.

Students using heroin most often also used opioids and benzodiazepines such as Xanax and Valium, the researchers report in Drug and Alcohol Dependence. Students who used heroin 10 to 39 times in the past month were most likely to use other drugs.

“Considering users’ overall drug use profiles appears to be important, because the concurrent use of multiple drugs can exacerbate adverse health effects associated with heroin use, such as overdose,” lead researcher Joseph Palamar said in a university news release. “A deeper understanding of how heroin users also currently use other drugs can help us to discern better prevention measures.”