In idiopathic intracranial hypertension (IIH) there is raised pressure within the skull (raised intracranial pressure), which puts pressure on the brain. Idiopathic means that the cause of this raised pressure is unknown. The main symptoms are headache and loss of sight (visual loss). It mostly affects women of childbearing age who are overweight or obese. Treatment is aimed at preventing permanent visual loss and includes treatment with medicines. Brain surgery (neurosurgery) may also be used. For many people, a combination of medical and surgical treatment can help to control their symptoms well.