To identify the symptoms and coexisting medical conditions associated with idiopathic intracranial hypertension (IIH), we administered an 83-item questionnaire at the time of diagnosis to 50 IIH patients and 100 aged-matched controls. Ninety percent of the IIH patients were women; the mean age was 33. Obesity and recent weight gain were much more common among patients than controls. Symptoms most commonly reported by IIH patients were headache (94%), transient visual obscurations (TVO) (68%), and intracranial noises (ICN) (58%). Daily occurrence of these symptoms was much more common among patients than controls. Controls also reported these and other IIH symptoms, but at lower frequencies. Several conditions previously associated with IIH were no more common in patients than controls including iron deficiency anemia, thyroid disease, pregnancy, antibiotic intake, and use of oral contraceptives. We conclude that previous studies of IIH, mostly uncontrolled and retrospective, have underestimated the frequency of symptoms in IIH patients and reported chance and spurious associations with common medical conditions and medications. The profile of a young obese woman with headaches and either TVO or ICN should alert the clinician to the diagnosis of IIH, especially when the symptoms occur daily.