ObjectiveTo describe and compare phenotypic features of posttraumatic headaches (PTH) and headaches unrelated to concussion.MethodsParticipants are a random sample of recently deployed soldiers from the Warrior Strong cohort, consisting of soldiers with (n = 557) and without (n = 1,030) a history of a recent mild traumatic brain injury (mTBI; concussion). mTBI+ soldiers were subdivided as PTH+ (n = 230) and PTH-(n = 327). Headache classification was based on a detailed phenotypic questionnaire. Medical encounters for headache were documented for the year after deployment.ResultsThe findings here are limited to the soldiers with headaches, consisting of 94% of the mTBI+ soldiers and 76% of the mTBI-soldiers. Other than headache duration, all headache/migraine features were more common or more severe in the PTH+ group compared to the nonconcussed group (mTBI-) and compared to the concussed group with nontraumatic headaches (PTH-). Headaches were largely similar in the mTBI-and PTH-groups. The features most specific to PTH+ included allodynia, visual aura, sensory aura, daily headache, and continuous headache. Medical consultation for headache was most common in the PTH+ group (62%) vs the PTH-group (20%) or the mTBI-group (13%) (p < 0.008).ConclusionsIn this cohort of recently deployed soldiers, PTHs are more severe, frequent, and migraine-like and more often associated with medical consultation compared to headaches presumed unrelated to concussion. Future observational studies are needed to verify and characterize the PTH phenotype, which could be followed by treatment trials with appropriate and possibly novel outcomes for prespecified subgroups.ClinicalTrials.gov identifierNCT01847040.