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.

More information about this treatment

This information is correct at time of publishing. But sometimes the types of cancer this treatment is used for, or treatment side effects, may change between revision dates.

You can talk to your cancer team if you want more detailed information about this treatment. Or visit the electronic Medicines Compendium (eMC) website, which has patient information leaflets (PIL) for individual drugs.

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 that are less common. 

You may get some of the side effects we mention, but you are unlikely to get all of them. And you may have some side effects, including rarer ones, that we have not listed here. 

Other cancer treatments may cause different side effects. If you are also having other cancer treatment, you may have other side effects.

Always tell your doctor, nurse or pharmacist about any side effects you have. They can give you: 

  • drugs to help control some side effects 
  • advice about managing side effects. 

It is important to take any drugs exactly as explained. This means they will be more likely to work for you.

Serious and life-threatening side effects

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

Contact the hospital

Your doctor, nurse or pharmacist will give you 24-hour contact numbers for the hospital. If you feel unwell or need advice, you can call at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.

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 on the 24-hour number for advice. They can give you drugs called laxatives to help. 

If you have not been able to pass stools for over 2 days and are being sick, contact the 24-hour number straight away. 

Skin changes

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

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

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 and increase the risk of diabetes. 

Signs of raised blood sugar include:

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

Tell your doctor or nurse if you have these symptoms. They can do tests to check your blood sugar level and give you advice.

If you already have diabetes, your blood sugars may be higher than usual. You may need to check them more often, or make changes to your diabetic treatment. Your diabetic doctor or nurse will talk to you about how to manage this.


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

If you are passing loose stools 3 or more times a day and this is not normal for you, contact the hospital as soon as possible on the 24-hour number. Follow the advice they give you about:

  • taking anti-diarrhoea medicines 
  • drinking enough fluids to keep you hydrated and to replace lost salts and minerals
  • any changes to your diet that might help. 

They might also ask you for a specimen of your stool to check for infection.

Fluid build-up

This treatment can cause a build-up of fluid in the body. This will slowly get better after treatment ends. Contact the hospital on the 24-hour number if you:

  • are gaining weight 
  • have swelling in your face, legs or ankles.

They can give you advice and treatment to help.

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 ends. 

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 feel:

  • very low in energy
  • breathless 
  • dizzy and light-headed. 

If you have these symptoms, contact the hospital straight away on the 24-hour number. You may need treatment for anaemia. 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, brown or purple spots that may look like a rash – these spots can be harder to see if you have black or brown skin. 

If you have any unexplained bruising or bleeding, contact the hospital straight away on the 24-hour number. 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. Contact the hospital straight away on the 24-hour number if you have any of these symptoms during or after treatment:

  • throbbing pain or swelling in a leg or arm
  • reddening of the skin in the area – if you have black or brown skin, this can be harder to notice, but the skin might become darker
  • suddenly feeling breathless or coughing.

Always call 999 if you have:

  • chest pain
  • difficulty breathing.

A blood clot is serious, but it can be treated with drugs called anticoagulants. These thin the blood. Your doctor, nurse or pharmacist can give you more information about preventing and treating blood clots.

Other important information

Other medicines

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


Doctors usually recommend that people with cancer have vaccinations for flu and for coronavirus (covid). These help reduce your risk of serious illness from these infections. Most people can have these vaccines, including people with weak immune systems.

If your immune system is weak, you should not have live vaccinations. Live vaccines can make you unwell because they contain a very weak version of the illness they will protect you against. Live vaccines include Zostavax®, which is a shingles vaccine, and the yellow fever vaccine.

It is important to ask your doctor, nurse or pharmacist for advice about having vaccinations. They can explain what vaccines are right for you and when it is best to have them.


Your doctor, nurse or pharmacist will advise you not to get pregnant or make someone pregnant while having this treatment and for some time afterwards. The drugs may harm a developing baby. It is important to use contraception to prevent pregnancy. Follow their advice about:

  • what types of contraception to use 
  • how long after treatment you should continue to use contraception. 


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

Your doctor, nurse or pharmacist 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 healthcare professional that you are having cancer treatment. Give them the contact details for your cancer doctor or cancer team so they can ask for advice.

If you have appointments with a dentist, always tell them you are having cancer treatment. Talk to your cancer team before you have any dental treatment.

About our information

  • Reviewers

    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.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

  • use plain English
  • explain medical words
  • use short sentences
  • use illustrations to explain text
  • structure the information clearly
  • make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.

Date reviewed

Reviewed: 01 August 2023
Next review: 01 August 2025
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.