Some veterans who are suffering from post-traumatic stress syndrome (PTSD), pain from injuries and other conditions have decided to stop taking the large amount of prescription drugs prescribed for them, without consulting their doctors.

NPR reports hundreds of thousands of veterans are taking opioids for pain. One in three veterans say they are on 10 different medications. Men and women in military service are prescribed narcotic painkillers three times more often than civilians, according to the article.

Some veterans have been prescribed drugs off-label, for conditions other than the ones approved by the Food and Drug Administration. Dr. Richard Friedman, Director of the Psychopharmacology Clinic at Weill Cornell Medical College, has studied the military’s use of antipsychotic drugs such as Seroquel and stimulants like Adderall and Ritalin. Those drugs do not have an official purpose in a combat zone, Friedman says. He assumes the military prescribed these medications to allow troops to sleep, wake up and function during wartime.

“They were in a different situation, where they had unprecedented levels of stress in a group of otherwise healthy people,” he said. “So, I think they resorted to psychopharmacology as a means to keep people in active duty.” Friedman warns that stopping medications without a doctor’s oversight can be harmful.

Earlier this year, the Department of Veterans Affairs (VA) initiated an Opioid Safety Initiative to reduce the use of opioids among veterans using VA health care. Gavin West, who heads the initiative, told NPR, “We’ve undertaken a psychopharmacologic safety initiative, where we’re looking across the board at more safe and more effective use of medications.”