“And we’re interested in looking at that and learning from that,” Shulkin said in the May 2017 statement. “But until the time that federal law changes, we are not able to be able to prescribe medical marijuana for conditions that may be helpful.”

One area researchers are exploring is the use of cannabis to help ease mental health problems that can lead to suicide among veterans. Other conditions cannabis is used for include nausea, epilepsy, and traumatic brain injury. Several countries, but not the U.S., have approved a cannabis-based drug to treat painful muscle spasms from multiple sclerosis.

It’s possible one group of cannabinoids may be responsible for both the high experienced by recreational users and the pain relief seen in some studies, said Dr. Winfried Hauser, a pain specialist at Klinikum Saarbrucken in Germany who wasn’t involved in the current studies.

Even though cannabis is legal for medical use in Germany, Hauser said many doctors hesitate to prescribe it because there aren’t well-defined recommended doses available. Vaporizers are difficult for many patients, and cannabis smoked in combination with tobacco can have dangerous side effects, Hauser added.

“Medical cannabis is no magic pill,” Hauser said.