Idiopathic intracranial hypertension (IIH) primarily affects young obese females, and potentially causes visual loss and severe headache. The aim of this experiment is to examine relapse rate and long-term outcome in IIH patients. The methods involved in this experiment include a prospective controlled study of 18 newly diagnosed IIH patients followed for a mean observation period of 21.1 (±8.0) months. Treatment regime included diuretics, dietary recommendations and check-up visits at a dietician. Baseline and follow-up included neurological examination, detailed headache history and comprehensive neuro-ophthalmological examination, including fundus photography, Humphrey visual fields, and measurement of the retinal thickness (RT) and retinal nerve fiber layers (RNFL) by optical coherence tomography (OCT). Relapse was defined as recurrence of either: (1) papilledema or (2) symptoms and demonstrated raised ICP. The result of this experiment is that relapse was found in 28%. Visual function improved from baseline to follow-up and was generally favorable. In patients without relapse of papilledema RT and RNFL were significantly thinner than in healthy controls (p = 0.003 and 0.02), although atrophy was clinically detectable in only one patient. Headache was still present in 67% of the patients at follow-up. Headache was heterogenic and unrelated to relapse. After an initial reduction, weight increased again in the relapse group compared to reduced weight in the non-relapse group (p = 0.013). Thus, the conclusions drawn are that headache was persistent, difficult to classify, and equally represented in relapse and non-relapse patients. Headache was thus a poor marker of active disease. Relapse rate was high and clinically undetectable optic disc atrophy was discovered in apparently well treated IIH patients.