Ottawa rule did not miss any important intracranial diagnosis in this cohort, including viral meningitis (n=6; 1.6%), subdural haematoma (n=3; 0.8%), intraparenchymal haemorrhage (n=5; 1.4%), arteriovenous malformation (n=2; 0.6%) and primary brain neoplasm (n=1; 0.3%). The scope of the Ottawa rule therefore may be wider than previously described and its clinical applicability may not be limited only to patients with a thunderclap headache. This study, however, is retrospective. These results should therefore be considered as hypothesis generating rather than confirmatory and would require validation within the context of a prospective study.The results of our study add to the growing body of evidence for the use of this tool and although it will not usurp the opinion of the clinician it may be helpful for risk stratification and to facilitate the discussion with radiological colleagues when requesting CT in patients with acute non-traumatic headache presenting to the emergency department. ■ As such, we would like to remind our colleagues to remember that the itchy (rash free) patient can be a classic presentation of iron deficiency (with or without anaemia). ■