Dual-hormone stress reactivity predicts downstream war-zone stress-evoked PTSD.

•We tested the singular and interactive effects of cortisol (CR) and testosterone (TR) reactivity as moderators of PTSD emergence in theater.•Blunted cortisol and testosterone stress reactivity at pre-deployment prospectively predicted PTSD symptom emergence in the war-zone.•This hormonal reactivity profile appears to confer increased risk for PTSD by potentiating the pathogenic effects of war-zone stressors.•Findings underscore the utility of assessing both HPA and HPG stress reactivity and may inform early detection of at risk soldiers for PTSD.