Colorado medical students are in favor of marijuana legalization but less certain about whether they will recommend cannabis to patients once they become doctors, according to the results of a new survey published this week.

Nearly two-thirds of the students surveyed at the University of Colorado School of Medicine said they support marijuana legalization, and almost half said they believe that marijuana can have physical health benefits. But only 29 percent of the students said they would recommend cannabis to a patient under the state’s current medical marijuana law, and other results hints at why.

More than three-quarters of students said they believe marijuana has the potential for psychological harm, and more than two-thirds said they believe it has the potential for physical harm. The students were nearly unanimous in saying that more research is needed on marijuana’s medical benefit.

“Despite strong support for marijuana legal reform, students expressed hesitancy to recommend it themselves, suggesting that medical students may not believe that there is enough data to safely recommend its use to patients and/or may not feel sufficiently trained to prescribe it,” Michael Chan, a recent CU graduate and one of the survey’s leaders, said in a statement. Chan is now a resident at the University of Texas Health Science Center.

The survey results were published earlier this week in the Journal of General Internal Medicine. Chan and his co-authors sent surveys to 624 medical students on CU’s Anschutz Medical Campus. They received responses from 236 students.

Students were more likely to be in favor of using cannabis medically if they were from Colorado or had used marijuana in the past.

Though the overall results show caution among medical students, they also suggest that younger doctors may be more receptive to recommending cannabis medically than the physician population as a whole. In a survey published in 2013, more than 500 Colorado doctors answered a similar survey. Nearly half of the doctors in that survey said doctors should never recommend cannabis as a therapy, and only 27 percent said they believed marijuana had physical health benefits.