Cetuximab (Erbitux®)

Cetuximab (Erbitux®) is used to treat bowel (colon and rectal) cancer and head and neck cancer. It may also be used to treat different types of cancer. Cetuximab belongs to a group of targeted therapy drugs called monoclonal antibodies. It is best to read this information with our general information about the type of cancer you have.

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 therapy.

Cetuximab is used to treat some head and 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.

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 cetuximab is given

You have cetuximab at a day unit. You may have it on its own or with radiotherapy or chemotherapy, depending on the type of cancer you have.

During treatment you usually see a:

  • cancer doctor 
  • cancer nurse or specialist nurse
  • specialist pharmacist. 

This is who we mean when we mention doctor, nurse or pharmacist in this information.

Before or on the day of each treatment, a nurse or person trained to take blood (phlebotomist) will take regular blood samples from you. This is to check that it is safe for you to have treatment. 

You will speak a doctor or nurse before you have treatment. They will talk to you about your blood results and ask how you have been feeling. If your blood results are okay, the pharmacy team will prepare your treatment.

You have cetuximab as a drip into a vein (intravenous infusion). The nurse will run the infusion through a pump. This will give you the treatment over a set time. 

You may have cetuximab through: 

  • a cannula – a short, thin tube the nurse puts into a vein in your arm or hand
  • a central line – a fine tube that goes under the skin of your chest and into a vein close by
  • a PICC line – a fine tube that is put into a vein in your arm and goes up into a vein in your chest
  • an implantable port (portacath) – a disc that is put under the skin on your chest or arm and goes into a vein in your chest.

You have the first infusion over 2 hours and then stay in the clinic for about 1 hour after. This is to check you do not have a reaction to the drug. If you do not have any problems, your next treatment can be given over 1 hour.

Your course of treatment

You may have cetuximab once a week or every 2 weeks. How long you have it for depends on the type of cancer you have. If you are having it with chemotherapy on the same day, you usually have chemotherapy 1 hour after the cetuximab. Your nurse, pharmacist or doctor will discuss your treatment plan with you.

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.

Side effects while treatment is being given

Some people may have side effects while they are being given this treatment or shortly after they have it.

Allergic reaction

Some people have an allergic reaction to cetuximab. This can happen while having the infusion or for up to 1 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 it can be more severe. If you have a reaction, the nurses can usually treat it by slowing or stopping the infusion. You will then have the rest of your treatments more slowly.

Your nurse will check you for signs of a reaction during your treatment. Always tell 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 or wheezy
  • swelling of your face or mouth
  • pain in your back, tummy (abdomen) or chest. 

Rarely, some people have 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 cetuximb 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, nurse or pharmacist if you have either of these allergies before they give you cetuximab.

Common side effects

Skin changes

This treatment often causes an acne-like rash or other skin changes such as dry, itchy or flaky skin. This most commonly affects the face, head and upper body. It is most likely to start in the first 3 weeks of treatment. Skin changes are more likely to happen if you have cetuximab with chemotherapy. 

Always tell your doctor, nurse or pharmacist about any skin changes. They can give you advice and prescribe creams or medicines to help. Do not use any over-the-counter acne products. These can make the skin changes worse.

If you have severe skin problems, your doctor may need to delay your next treatment or lower the dose.

Skin changes usually improve after 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 and calcium in the blood

You will have regular blood tests to check the levels of magnesium and calcium in your blood. Your doctor may prescribe 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, at night and after meals. Use a soft-bristled or children’s toothbrush. Your nurse can give you advice on looking after your mouth and may give you a mouthwash to use.


Feeling tired is a common side effect. Try to pace yourself and get as much rest as you need. Some gentle exercise may help, such as short walks. If you feel sleepy, do not drive or operate machinery.


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 or a mild increase in stoma activity:

  • follow any advice from your cancer team about taking anti-diarrhoea drugs
  • drink at least 2 litres (31/2 pints) of fluids each day
  • avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods.

Contact the hospital straight away if:

  • you have diarrhoea at night
  • you have diarrhoea more than 4 times in a day 
  • you have a moderate or severe increase in stoma activity 
  • the anti-diarrhoea drugs do not work within 24 hours.

Hair changes

Your eyelashes may grow longer and curlier. You may notice that your head and body hair is finer, curlier or more brittle. Men may notice less beard growth. Some people may lose their hair. This may happen slowly over several months. These changes usually improve after treatment has finished. We have more information about coping 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. They can give you advice.

There are things you can do to look after your nails:

  • Moisturise your nails and cuticles regularly.
  • Keep your nails clipped short.
  • Wear gloves to protect your nails when you are doing things in the house or garden.
  • Keep your hands and nails clean to help avoid infection, but avoid bathing in very hot water.
  • Do not use false nails, gels or other acrylics during this treatment, as they may increase the risk of infection.
  • It is fine to wear nail varnish, but try to use a water-based polish. Avoid using harsh chemicals, such as acetone, when taking off the polish.
  • If your toenails are affected, wear well-fitted shoes to cushion them.

Tell your doctor or nurse if you notice changes to your nails. They can give you advice or arrange for you to see a podiatrist for foot care advice if needed.

Feeling sick

Your doctor, nurse or pharmacist will prescribe anti-sickness drugs to help prevent or control sickness. Take the drugs exactly as they tell you to, even if you do not feel sick. It is easier to prevent sickness than to treat it after it has started.

If you feel sick, take small sips of fluid often and eat small amounts regularly. It is important to drink enough fluids. If you continue to feel sick, or if you are sick (vomit) 1 to 2 times in 24 hours, contact the hospital on the 24-hour number as soon as possible. They will give you advice. They may change your anti-sickness treatment. Let them know if you still feel sick.

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.


This treatment may cause headaches. If you have headaches, tell your doctor, nurse or pharmacist. They can give you advice about painkillers that may help. Tell them if the headache does not get better, or gets worse.

Liver changes

This treatment can cause changes to the lungs. Contact the hospital straight away if you notice any of these changes during treatment or after it finishes:

  • breathlessness
  • a cough
  • wheezing
  • a fever, with a temperature over 37.5°C (99.5°F).

You may have inflammation of the lungs. You should also tell your doctor if any existing breathing problems get worse. You may have tests to check your lungs. Your doctor can tell you more about this.

Less common side effects

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 treatment. 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. If you cannot get through to your doctor, call the NHS urgent advice number on 111.

Other information

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 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 at least 2 months after your last dose. 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 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
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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 November 2023
Next review: 01 November 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.