Assessing the safety and effectiveness of a 11-βhydroxysteroid dehydrogenase type 1 inhibitor (AZD4017), in a placebo controlled trial, in acute idiopathic intracranial hypertension (IIH) IIH is a condition of young, overweight women with characteristic raised intracranial pressure (pressure around the brain) leading to papilloedema (swelling of the nerve supplying the eye), visual loss and headaches. Medical literature (Cochrane review) demonstrates there is little evidence for the treatments used for IIH. Weight control appears the most effective method of improving symptoms but weight loss is difficult to maintain. 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) is an enzyme which regulates local steroid levels and our previous research suggests it may influence the production of brain fluid(cerebrospinal fluid or CSF). 11β-HSD1 levels fall with weight loss and this is associated with with decreased intracranial pressure.