Gliadel wafers

Gliadel® wafers are small discs that contain the chemotherapy drug carmustine. They are about the size of a 5 pence (5p) coin. They are sometimes used to treat a type of brain tumour called a glioma. They are used along with surgery or radiotherapy, or both.

It is best to read this information with our information about chemotherapy for brain tumours and the type of brain tumour you have. 

Your doctor, nurse or pharmacist will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.

How Gliadel wafers are given

You have a small operation to place Gliadel wafers in the area where the brain tumour was removed. The operation is done by a surgeon who specialises in brain surgery (neurosurgeon).

Usually, up to 8 wafers are used. The wafers release a chemotherapy drug called carmustine directly to the surrounding cells. This usually takes around 2 to 3 weeks. As they release the drug, the wafers dissolve. This means they do not need to be removed.

Gliadel wafers may only be suitable in certain situations. Your surgeon will tell you whether they are suitable for you before your operation. But your surgeon may not know whether they can insert the wafers until you are having your operation. Some people are given Gliadel wafers as part of a clinical trial.

About side effects

We explain the most common side effects of this treatment here. We also include some less common side effects.

You may get some of the side effects we mention, but you are unlikely to get all of them. If you are also having treatment with other cancer drugs, you may have some side effects that we have not listed here. Always tell your doctor, nurse or pharmacist about any side effects you have.

Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist explains. This means they will be more likely to work for you. Your nurse will give you advice about managing your side effects. After your treatment is over, most side effects start to improve.

Serious and life-threatening side effects

Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.

Contact the hospital

Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.

More information

We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.

Possible side effects of Gliadel wafers

Possible effects on the nervous system

Gliadel wafers may have some effects on the nervous system. This can also happen after surgery to the brain. Your doctors and nurses will monitor you very closely.

Seizures (fits)

You may be more likely to have seizures (fits). They are most likely to happen within the first 5 days after your operation. Your doctor may prescribe medicines for a short time to help prevent them. If you have been having seizures already, you can talk to your surgeon about the medicines you take.

Headaches and dizziness

Headaches and dizziness are common after brain surgery and with Gliadel treatment. Your doctor will tell you which painkillers will help. Tell them if the headaches or dizziness get worse. 

Temporary swelling in the brain

Gliadel wafers may cause swelling in the brain. This is usually temporary. It can also happen after surgery to the brain. Your doctor or nurse will usually give you steroids to help reduce swelling.

Tell your doctors or nurse straight away if you: 

  • have severe headaches
  • feel weak in your arms or legs (on one or both sides) 
  • have difficulty walking
  • feel confused, drowsy or sleepy
  • have difficulty speaking
  • feel sick (nauseas) or are sick (vomit).

If someone with you notices you have these symptoms, they should contact the hospital straight away.

An infection in the brain

Your doctors and nurses will be checking you closely for any signs of infection. Tell them if you have:

  • a temperature
  • flu-like symptoms
  • headaches
  • neck stiffness
  • sensitivity to bright light.

Mood changes

This treatment can cause changes in your mood. If you feel low, depressed or anxious, tell your cancer doctor, nurse or GP. They can help get you the support you need.

Other side effects

Lower number of white blood cells

This treatment can reduce the number of white cells in your blood. These cells fight infection. This is rare with Gliadel wafers because not much of the carmustine drug is absorbed into the bloodstream. This means there is less risk of infection than with chemotherapy that goes into a vein. But it can still happen. Tell your doctor or nurse if you have any signs of an infection. 

Signs of an infection include:

  • a cough
  • a sore throat
  • diarrhoea
  • needing to pass urine (pee) often or not passing urine. 

Contact your doctor or the hospital straight away if:

  • your temperature goes over 37.5°C (99.5°F)
  • your temperature goes below 36°C (96.8°F)
  • you suddenly feel unwell, even with a normal temperature.


This treatment can cause constipation. Constipation means that you are not able to pass stools (poo) as often as you normally do. It can become difficult or painful. Here are some tips that may help:

  • Drink at least 2 litres (3½ pints) of fluids each day.
  • Eat high-fibre foods, such as fruit, vegetables and wholemeal bread.
  • Do regular gentle exercise, like going for short walks.

If you have constipation, contact the hospital for advice. Your doctor can give you drugs called laxatives to help.

Skin changes

This treatment may affect your skin. It may cause a rash, which might be itchy. Your doctor or nurse can tell you what to expect. If your skin feels dry, try using an unperfumed moisturising cream every day.

Always tell your doctor or nurse about any changes to your skin. They can give you advice and may prescribe creams or medicines to help. Skin changes usually improve when treatment finishes.

Slow wound healing

It may take longer for your wound to heal after your operation. This is because the Gliadel wafers can affect the healing process. Your doctor or nurse will check your wound regularly. If you notice any leaking from the wound, or swelling or redness in the area, tell your doctor or nurse straight away.

Eyesight changes

This treatment can affect your eyes and eyesight. If you have any of these symptoms during treatment or after it finishes, contact your doctor straight away:

  • sore or swollen eyes
  • changes to your eyesight.

Raised blood sugar levels

This treatment can raise your blood sugar levels. If you have a raised blood sugar level, you may:

  • feeling thirsty
  • needing to pass urine (pee) more often
  • feeling tired.

Tell your doctor or nurse if you have these symptoms.

If you have diabetes, your blood sugar levels may be higher than usual. Your doctor will talk to you about how to manage this. You may need to change your insulin or tablet dose.


This treatment may cause diarrhoea. Diarrhoea means passing more stools (poo) than is usual for you, or having watery or loose stools. If you have a stoma, it will be more active than usual.

If you have diarrhoea:

  • try to drink at least 2 litres (3½ pints) of fluids each day
  • avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods
  • contact the hospital for advice.

Fluid build-up

You may gain weight, or your face, ankles and legs may swell. This improves slowly after your treatment has finished. Your doctor may give you drugs to help reduce the swelling.

Low sodium and potassium levels in the blood

Your doctor will check your sodium and potassium levels with a blood test. Low levels of sodium can cause tiredness, muscle twitching, and sometimes seizures (fits).

Low levels of potassium can cause muscle weakness and twitching, and sometimes an irregular heart rhythm.

Tell your doctor or nurse if you notice any of these symptoms.

Hair loss

Your hair may get thinner. But you are unlikely to lose all the hair from your head. Hair loss usually starts after your first or second treatment. It is almost always temporary, and your hair will usually grow back after treatment finishes. Your nurse can talk to you about ways to cope with hair loss.

Anaemia (low number of red blood cells)

This treatment can reduce the number of red blood cells in your blood. Red blood cells carry oxygen around the body. If the number of red blood cells is low, this is called anaemia. You may have symptoms such as:

  • pale skin
  • lack of energy
  • feeling breathless
  • feeling dizzy and light-headed.

Tell your doctor or nurse if you have these symptoms.

If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.

Bruising and bleeding

This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot.

If the number of platelets is low, you may bruise or bleed easily. You may have:

  • nosebleeds
  • bleeding gums
  • heavy periods
  • blood in your urine (pee) or stools (poo)
  • tiny red or purple spots on the skin that may look like a rash.

Tell your doctor if you have any unexplained bruising or bleeding. You may need a drip to give you extra platelets. This is called a platelet transfusion.

Blood clot risk

Cancer and some cancer treatments can increase the risk of a blood clot. Symptoms of a blood clot include:

  • throbbing pain, redness or swelling in a leg or arm
  • suddenly feeling breathless or coughing
  • sharp chest pain, which may be worse when you cough or take a deep breath.

If you have any of these symptoms, contact the hospital straight away on the 24-hour contact number you have been given. If you cannot get through to your doctor, call the NHS urgent advice number on 111.

A blood clot is serious, but it can be treated with drugs that thin the blood (anticoagulants). Your doctor or nurse can give you more information.

You can help reduce the risk of developing a blood clot by:

  • staying active during treatment
  • drinking plenty of fluids, especially water.

You may be given anticoagulants to help prevent a clot.

Other important information

Other medicines

Some medicines can affect how this treatment works or be harmful when you are having it. Always tell your cancer doctor about any drugs you are taking or planning to take, such as:

  • medicines you have been prescribed
  • medicines you buy in a shop or chemist
  • vitamins, herbal drugs and complementary therapies.

Tell other doctors, pharmacists or dentists who prescribe or give you medicines that you are having this cancer treatment.

You can visit the electronic Medicines Compendium (eMC) for more detailed information about your treatment.


Vaccinations can reduce your risk of getting certain infections. Your doctor or nurse may talk to you about having vaccinations.

Doctors usually recommend that people with cancer have a flu vaccination and a coronavirus (covid) vaccination. These are both inactivated vaccinations that can help reduce the risk of infection. People with weak immune systems can have these, as they are not live vaccinations. 

If your immune system is weak, you need to avoid live vaccinations. This is because they can make you unwell. Live vaccines contain a very weak version of the illness they are vaccinating you against. Your cancer doctor or GP can tell you more about live and inactivated vaccinations.


Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment. The drugs may harm a developing baby. It is important to use contraception during your treatment and for a while after treatment finishes. Your doctor, nurse or pharmacist can tell you more about this.


You are advised not to breastfeed while having this treatment, or for some time after treatment finishes. This is because the drugs could be passed to the baby through breast milk.

Your doctor or nurse can give you more information.


Some cancer drugs can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor before you start treatment.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses you are having cancer treatment. Give them the contact details for your cancer doctor so they can ask for advice.

If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having cancer treatment.

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    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert health professionals and people living with cancer.

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