A common anti-anxiety drug may help reduce post-traumatic stress disorder (PTSD) if given promptly after a traumatic incident. Promising results from a small study in France show that the drug may be an inexpensive and effective treatment for the disorder.

In two French emergency rooms, doctors offered the anti-anxiety drug propranolol to patients within two to 20 hours after a traumatic injury. These patients were medically stable but had tachycardia--an elevated heart rate and known indicator of a panic reaction. If, after lying down for 20 minutes, the heart rate remained higher than 90 beats a minute, the patients were offered the drug.

Two months later, patients who had declined drug treatment experienced stress symptoms that were twice as severe. Three out of those eight patients developed full-blown cases of PTSD. Of those who took propranolol, only one person of 11 was diagnosed with the disorder.

The University of California at San Francisco’s Charles Marmarr, senior author of the study, suggests that PTSD occurs most often in patients who have an especially robust and prolonged negative reaction to trauma. Normally, the stress response--the fight or flight reaction--lasts only a few minutes. Yet for a quarter of the population, it can last for hours or days, which can greatly increase the odds of developing a stress disorder. Marmarr hopes that quickly calming such patients will prevent PTSD from developing.

The study was published in the November issue of Biological Psychiatry.