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Idiopathic Intracranial HypertensionIdiopathic Intracranial Hypertension

What is IIH?

What is Idiopathic Intracranial Hypertension?

Our brain is protected by a fluid called cerebrospinal fluid (CSF), and when someone has IIH, their body is unable to properly absorb or drain the CSF. The average adult replenishes CSF roughly 3-4 times a day, so when this is either interrupted or too much is produced, this leads to painful headaches and symptoms such as dizziness and memory problems, because intracranial pressure increases. As this is a neurological condition, it isn't something you can see, which means that the person with IIH doesn't look ill and can mistakenly be thought of as perfectly well.

It was previously known as Benign Intracranial Hypertension and Pseudotumor Cerebri, although some clinicians still use these names. It affects around 1-2 in every 100,000, but in the UK there are thought to be around 540 people with IIH, but the numbers are rising due to the prevalence of obesity, which makes up a large percentage of people with IIH. However, this does not necessarily mean that obesity is the sole cause of IIH, there are, as you will discover, other causes.. 

 Main Symptoms are:

Chronic headache

Whooshing noise in the ear/s

Grey spots sometimes described as cobwebs or wisps, and blobs in one or both eyes.

Other symptoms

Nausea & vomiting
• Neck stiffness
• Dizziness
• Depression
• Lethargy
• Memory issues
• Exercise intolerance
• Heat intolerance
• Pain in arms, legs & back
• Tingling in hands & Spinal fluid leaks from nose - (Cerebral Fluid Rhinorrhea - this is rare)

Causes of IIH

This is not known which is why it is called idiopathic.

Risk factors for IIH

Obesity, Pregnancy, PCOS, vitamin D deficiency, Cushing's Syndrome, Hypoparathyroidism, underactive thyroid, certain medications such as Tetracycline, Steroid medication,excessive vitamin A and oral contraceptives, Lupus, Meningitis, chronic kidney failure, anaemia

 Join our IH.CONNECT Registry

We hope you’ll consider joining the IIH.Connect registry it could help you to find a Specialist in or around your area.




We are grateful to the Big Lottery Fund for providing the support and funding to enable us to produce these booklets, and distribute them to hospitals in the UK.We are grateful to the Big Lottery Fund for providing the support and funding to enable us to produce these booklets, and distribute them to hospitals in the UK.

IH Information Booklets

Just diagnosed - What is IIH? An Introduction to Idiopathic Intracranial Hypertension

Diagnostic Tests for IIH

Medical Treatment and Monitoring of IIH

Surgical Treatment for Severe IIH

Our booklets are available in hardcopy which you can request by contacting us.



A-Z of Other Headaches Common with IIH

Common Shunt Blockage/Infection Symptoms and Other Information

Low Pressure Headaches and How to Deal with Them

Questions to Ask the Doctor 


IIH Symptoms Diary

Activity Diary Manager

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