This study compared the relative effectiveness of treating migraines by with chiropractic care alone, with the antidepressant/antianxiety drug amitriptyline (best known under the brand name Elavil); and with a combination of both the drug therapy and chiropractic care. Patients who received only chiropractic showed significant improvement, on a par with those given the powerful prescription drug (though without the side effects). The headache index, from a diary kept by each patient, showed chiropractic to have reduced the severity and frequency of headaches as well or better than the combined therapy or amitriptyline alone at each stage of the study.
Nelson CF, Bronfort G, Evans R, et al. J Manipulative Physiol Ther. 1998 (Oct); 21 (8): 511-519