title: Histamine H2 antagonists and cluster headache.
mesh_terms: D002986:Clinical Trials as Topic; D006146:Guanidines / Q000627:therapeutic use*; D006261:Headache / Q000188:drug therapy*; D006801:Humans; D007093:Imidazoles / Q000627:therapeutic use*; D008297:Male; D014653:Vascular Headaches / Q000188:drug therapy* / Q000209:etiology
chemical_list: D006146:Guanidines; D007093:Imidazoles