Cetuximab (Erbitux®)

Cetuximab (Erbitux®) is a targeted therapy drug. It used to treat bowel cancer (colon and rectum), and head and neck cancer.

What is cetuximab (Erbitux®)?

Cetuximab (Erbitux®) is used to treat bowel (colon and rectum) cancer, and head and neck cancer. It is best to read this information with our general information about the type of cancer you have.

Cetuximab belongs to a group of targeted therapy drugs known as monoclonal antibodies.

Cetuximab is used to treat advanced bowel cancer when tests show the cancer cells do not have a change (mutation) in a gene called RAS. It is usually given with chemotherapy or sometimes targeted therapies.

Cetuximab is used to treat some head and neck cancers which have spread. It may be given with radiotherapy or chemotherapy.

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

How cetuximab is given

You will be given cetuximab at a day unit. Cetuximab can be given on its own or in combination with other cancer drugs. 

During treatment you usually see a cancer doctor, a cancer nurse or specialist nurse, and a specialist pharmacist. This is who we mean when we mention doctor, nurse or pharmacist in this information.

You will see a doctor or nurse before you have treatment. They will ask you how you have been feeling. Your nurse will tell you when your treatment is likely to be ready. Your nurse, pharmacist or doctor will discuss your treatment plan with you.

Cetuximab is given as a drip into a vein (intravenous infusion). It is usually given using a pump that controls the rate of the drip. 

You have the first treatment slowly, over about 2 hours. If you do not have any problems, you can have your next treatment over 1 hour. Afterwards you stay in the clinic for about an hour. This is so the nurses can be sure you do not have a reaction to the drug. 

You usually have cetuximab once a week. If you are having chemotherapy on the same day, you usually have it an hour after cetuximab. 

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 chemotherapy or radiotherapy, 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.

Side effects during treatment

Allergic reaction

Some people have an allergic reaction to cetuximab. This can happen while having the treatment or for up to an hour afterwards. You will be given drugs before the infusion to reduce the chance of a reaction happening.

A reaction is usually mild but, rarely, can be more severe. If you have a reaction, the nurses can usually treat it by slowing or stopping the drip. Then you will have the rest of your treatments more slowly.

Your nurse will check you for signs of a reaction during your treatment. Always tell your them straight away if you feel unwell or have any of the following symptoms:

  • feeling hot or flushed
  • a skin rash
  • itching
  • shivering
  • feeling dizzy
  • a headache
  • feeling breathless
  • swelling of your face or mouth
  • pain in your back, tummy or chest.

Rarely, people may get a reaction a few hours after treatment. If you have any of the symptoms above or feel unwell after you get home, contact the hospital straight away for advice.

You are more likely to have a serious allergic reaction to cetuximab if you have an allergy to:

  • red meat
  • tick bites (a tick is a tiny spider-like insect found in woodland and heath areas).

You must tell your cancer doctor and nurse if you have either of these allergies before they give you cetuximab.

Common side effects

Skin changes

Cetuximab often causes an acne-like rash or other skin changes such as dry, itchy or flaky skin. This is most likely to start in the first 3 weeks of treatment.

Always tell your doctor or nurse about any skin changes. They can give you advice and prescribe creams for your skin or medicines to help. If you have severe skin problems, your doctor may need to delay your next treatment or lower the dose.

Skin changes usually improve when treatment finishes. We have information about coping with skin changes during treatment.

Very rarely, cetuximab causes a very severe skin reaction. Contact the hospital straight away if you have:

  • a rash that blisters or peels
  • sores on your lips or in your mouth
  • flu-like symptoms or a fever (high temperature).

Reduced levels of magnesium in the blood

Magnesium helps keep nerves and muscles working properly. You will have regular blood tests to check your levels of magnesium. Your doctor may prescribe you magnesium supplements if the levels are too low.

Sore mouth and nose

The lining of your mouth and nose may become sore. You may have mouth ulcers or nosebleeds. Tell your nurse or doctor if you have any of these changes. They can give you medicines to help.

Clean your teeth or dentures morning and night and after meals. Use a soft-bristled or children’s toothbrush. Your nurse can give you advice on looking after your mouth.


Feeling tired is a common side effect. Try to pace yourself and plan your day so you have time to rest. Gentle exercise, like short walks, can give you more energy. If you feel sleepy, do not drive or operate machinery.


If you have diarrhoea, it can usually be controlled with medicines. Follow any advice you have been given about taking anti-diarrhoea drugs. Tell your doctor if the diarrhoea is severe or if continues after taking the anti-diarrhoea drugs. It is important to drink at least 2 litres (3½ pints) of fluids each day. This stops you getting too dehydrated. It can help to avoid:

  • alcohol
  • caffeine
  • milk products
  • high-fat foods
  • high-fibre foods.

Hair changes

Your eyelashes may grow longer and more curly than usual. You may notice your head and body hair becomes finer, curlier or more brittle. Some people may lose their hair slowly over several months. These changes are usually temporary and gradually improve after treatment has finished. Your nurse can talk to you about ways to cope with hair loss.

Nail changes

You may notice changes to your nails. They may become brittle and break easily. Wear gloves when washing dishes or using detergents to help protect your hands and nails. If the area around your nails becomes inflamed, tell your doctor straight away.

Liver changes

This treatment may cause changes in the way your liver works. This will return to normal when the treatment finishes. Your doctor or nurse will take regular blood samples to check your liver is working properly.

Less common side effects

Feeling sick

Your doctor can prescribe anti-sickness drugs to help prevent or control sickness. If you still feel sick, tell your doctor. They can prescribe other anti-sickness drugs that may work better for you.


This treatment may cause headaches. If you have headaches, tell your doctor. They may give you painkillers to help.

Sore eyes

Cetuximab may make your eyes dry, sore, red and itchy. Your doctor can prescribe eye drops to help with this.

Tell your doctor if

  • your eyes do not improve after taking the eye drops
  • you have changes to your vision
  • you have pain in your eye.

Sometimes cetuximab may cause inflammation of the eyelid. It is important to contact your doctor straight away if this happens.

Effects on the lungs

This treatment can cause changes to the lungs. Tell your doctor if you develop:

  • a cough
  • wheezing
  • a fever (high temperature)
  • breathlessness.

You should also tell them if any existing breathing problems get worse. You may have tests to check your lungs.

If your symptoms develop suddenly, contact the hospital immediately. You may have inflammation of the lungs (pneumonitis). Your doctor can tell you more about this.

Effects on the heart

Rarely, this treatment can affect the way the heart works. This may be more likely if you are having it with other types of anti-cancer treatments. Your doctor can tell you more about this.

You may have tests to see how well your heart is working. These may be done before, during, and sometimes after treatment.

Contact a doctor straight away if you:

  • have pain or tightness in your chest
  • feel breathless or dizzy
  • feel your heart is beating too fast or too slowly.

Other conditions can cause these symptoms, but it is important to get them checked by a doctor.

Other information

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 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.

Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

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