What is Idiopathic Intracranial Hypertension  (IIH)?

IIH is a condition where the fluid surrounding the brain is at a higher pressure than normal. This fluid, which is similar to water, is called cerebrospinal fluid (CSF). As well as surrounding the brain, it also surrounds the spinal cord as well as the optic nerves that carry information about vision from our eyes to our brain. This causes the optic nerves inside the eye to look swollen, which may be the first sign of IIH picked up by your optometrist or specialist.


’Idiopathic’ is a medical term which means that the cause is not known. However, there are important factors that increase the risk of getting the condition:

  • The most common risk factor is gaining weight or being overweight.

  • Certain medications increase a person’s chance of suffering from IIH. These include tetracycline antibiotics, steroids, high doses of vitamin A and growth hormone.


  • Headache is the most common symptom. Some people get headaches even after the high pressure in the CSF is treated.

  • Some people experience temporary loss of vision in one or both eyes which can last seconds, especially when straining or bending over. These are called ‘visual obscurations’.

  • There may be other disturbances of vision such as blurred vision, dimming of vision, losing parts of the vision, double vision, seeing flashing lights or problems with seeing colours.

  • A ‘whooshing’ noise in the ears may occur.

  • Some people with IIH have no symptoms at all and the condition is picked up at a routine eye test.


Weight loss is the most important treatment for IIH. Many medical research studies have shown that losing weight is very effective at reducing the fluid pressure, headaches and problems with vision. Research suggest that weight loss of 5-10% will significantly improve the condition. Your eye specialist may refer you to your GP to start a weight loss programme.

Your doctors may prescribe a medicine that will help lower the fluid production in your body. Medications must be used alongside weight loss. Surgery is only considered when weight loss and medications have failed and there are significant visual problems arising from the condition. Your eye specialist will refer you to a neurosurgeon if these treatments are needed.


It is safe to fly with this condition as long as you feel well in yourself. When travelling it is important that you have valid travel insurance. You should inform your insurance company that you have IIH and ensure you read the small print to see what the insurance will cover. Make sure you take your medications with you so you don’t run out whilst abroad.

There is some suggestion that the combined oral contraceptive pill may increase the risk of IIH but this has not been confirmed. Medicated intrauterine implants may also increase this risk.

Many women with IIH are taking the pill but this may just be a coincidence. Your doctor may suggest that if you feel that the pill has increased your symptoms, you should use an alternative form of contraception that does not contain oestrogen (discuss the options with your GP).

It is advisable to speak to your eye specialist before planning a pregnancy.

If your IIH is not well-controlled your doctor may recommend that you wait until your health is more settled. There is no evidence that pregnancy itself causes IIH or makes it worse. However, gaining excessive weight during pregnancy will often make the condition worse.

The medications used to treat IIH may pose a risk to the unborn baby. Therefore you must inform your doctor if you are pregnant or are thinking of getting pregnant as your medication may need to be changed.

There is no need to have a caesarean section if you have IIH unless it is needed for another reason. A normal vaginal delivery is safe. It is also safe to have a lumbar puncture if it is required during pregnancy.

The main risk of IIH, if it remains untreated, is permanent damage to the vision. Fortunately this is rare but if you are concerned that your vision has deteriorated you should seek medical attention urgently.

Some patients’ symptoms improve quickly with weight loss alone. If medications are required, most people are able to do without these after a few years.

Some patients with IIH continue to be prone to headaches even after the high CSF pressure is effectively treated and remains normal. These headaches are often similar to migraines and are treated in a similar way, usually by your GP or a neurologist.