Last Updated on November 8, 2026

For a full explanation of IIH, its symptoms, tests and treatment, see our page on idiopathic intracranial hypertension (IIH).

What is idiopathic intracranial hypertension (IIH, also called benign intracranial hypertension)?

Idiopathic intracranial hypertension is a condition that causes the pressure in the fluid system of the brain to go up. It can have a number of effects, including causing headaches, pulsatile tinnitus (a whooshing sound in the ears), dizziness, a dislike of bright lights (photophobia), neck pain, and visual loss (the most serious of the consequences of the condition).

How is IIH treated? What the 2015 trial found

Treatment includes weight loss and a drug called acetazolamide, as well as shunting of the fluid and vein stenting where appropriate.

Finally, a clinical trial demonstrates that the diet and the drug also are effective.

The trial consisted of 165 newly diagnosed untreated patients who were prescribed a low-calorie diet, provided with a weight-loss counselor, and randomly assigned to either daily acetazolamide or placebo (non-active drug).

The results, presented at the North American Neuro-Ophthalmology Society 2015 Annual Meeting, showed those given drug lost 6% of their body weight compared to 3% on the diet alone. Vision measures improved in the acetazolamide group, but seemed to get worse in the diet only group, these included a number of objective measures of disc swelling.

North American Neuro-Ophthalmology Society (NANOS) 2015 Annual Meeting. Presented February 25, 2015.