Encorafenib (Braftovi ®) and cetuximab (Erbitux®)

Encorafenib (Braftovi®) and cetuximab (Erbitux®) is a treatment that combines 2 targeted therapy drugs.

Encorafenib belongs to a group of targeted therapy drugs known as cancer growth inhibitors. Cetuximab belongs to a group of targeted therapy drugs known as monoclonal antibodies. 

It is best to read the information about this drug with our general information about targeted therapy drugs and the type of cancer you have. 

Your cancer 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 encorafenib and cetuximab is given

You will be given this treatment at a day unit as an outpatient.

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 a blood sample from you. This is to check that it is safe for you to have treatment.

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

Cetuximab is given as a drip into a vein (intravenous infusion). The nurses will give you the first treatment over about 2 hours. If you do not have a reaction, you can have the next cetuximab treatment over 1 hour. 

Encorafenib is given as capsules. A nurse or pharmacist will give you them to take home. You may be given capsules of different strengths. Always take them exactly as explained. This is important to make sure they work as well as possible for you.

They may also give you anti-sickness drugs and other medicines to take home. You should take all your capsules or tablets exactly as they have been explained to you.

Your course of treatment

Your doctor, nurse or pharmacist will discuss your treatment plan with you. 

You usually have a course of several cycles of treatment over a few months. Each cycle lasts 28 days. You usually have cetuximab on day 1 and day 15. You take encorafenib once a day every day. 

You can continue to have encorafenib and cetuximab for as long as it is working for you and if the side effects are manageable.

Taking encorafenib capsules

You can take encorafenib with or without food. They must be swallowed whole with a glass of water. They should not be chewed, opened or crushed. Take them at the same time every day.

Avoid eating grapefruit or drinking grapefruit juice when taking encorafenib. They may make the side effects worse. 

If you forget to take the capsules you should take the missed dose if it is more than 12 hours until your next dose. If it is less than 12 hours wait and take the next dose at your usual time. Do not take a double dose unless your doctor tells you to.

Other things to remember about your capsules/tablets:

  • Keep them in the original package and at room temperature, away from moisture, heat and direct sunlight.
  • Keep them safe, somewhere children cannot see or reach them.
  • If you are sick just after taking the capsules or tablets, contact the hospital. Do not take another dose.
  • If your treatment is stopped, return any unused capsules/ tablets to the pharmacist.

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. 

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 treatment 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, 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 and for a while after 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

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.

Feeling tired (fatigue)

Feeling tired is a common side effect. Try to pace yourself and plan your day so you have time to rest between activities.

Being physically active can help to manage tiredness and give you more energy. It also:

  • helps you sleep better
  • reduces stress
  • improves your bone health.

If you feel sleepy, do not drive or operate machinery.

Skin changes

This treatment 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.

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).

Hand foot syndrome

This treatment can affect the palms of your hands and the soles of your feet. The skin may become sore. If you have white skin these areas may become red. If your skin is black or brown these areas might get darker. You may also have pain, tingling, or swelling in your palms or soles. The skin may peel or sometimes crack or blister. This is called palmar-plantar or hand-foot syndrome. 

If you have any of these symptoms, contact the hospital for advice on the number you were given. They can prescribe creams and painkillers to help. You can take care of your hands and feet by:

  • taking cool showers or baths to keep your hands and feet cool
  • moisturising your hands and feet regularly
  • avoiding tight-fitting socks, shoes and gloves.


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.


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. 

Tummy pain

You may get pain in your tummy (abdomen), or have indigestion. Your doctor, nurse or pharmacist can give you advice or treatment to help. Contact the hospital straight away on the 24-hour number if your symptoms do not go away, or get worse.

Loss of appetite

This treatment can affect your appetite. Don’t worry if you do not eat much for 1 or 2 days. But if your appetite does not come back after a few days, or if you are losing weight, tell your doctor, nurse or pharmacist. They can give you advice. They may give you food or drink supplements. Or they may suggest changes to your diet or eating habits to help.

Changes to your taste

Some foods may taste different or have no taste. Try different foods to find out what tastes best to you. You may also get a bitter or metallic taste in your mouth. Your doctor, nurse or pharmacist can give you advice. It might help to try:

  • sucking sugar-free sour or boiled sweets
  • eating cold foods
  • eating sharp-tasting fresh fruit.

Taste changes usually get better after treatment ends. We have more information about coping with changes to taste.

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.

Muscle or joint pain

This treatment can cause pain in your muscles or joints. If this happens, tell your doctor so they can give you painkillers. Tell them if the pain does not get better.

Difficulty sleeping

You might have difficulty sleeping. We have tips on things you can do to improve sleeping. If it does not get better talk to your doctor or nurse.


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.

Numb or tingling hands or feet (peripheral neuropathy)

This treatment may affect the nerves in your fingers and toes. This can cause numbness, tingling or pain in your hands or feet. This is called peripheral neuropathy. You might find it hard to do fiddly tasks such as fastening buttons or tying shoelaces.

If you have these symptoms, always tell your doctor, nurse or pharmacist. They sometimes need to change the drug or the dose of the drug. The symptoms usually improve slowly after treatment ends. But for some people they continue and are a long-term side effect of treatment.


This treatment may increase your risk of bleeding. Tell your doctor if you have any bruising or bleeding that you cannot explain. This includes:

  • nosebleeds
  • blood in your pee (urine) or poo (stools)
  • bleeding from the back passage (rectum).

Liver changes

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

Kidney changes

This treatment can affect how your kidneys work. You will have blood tests to check how well your kidneys are working. Tell your doctor or nurse if you have blood in your urine (pee) or you are passing urine less than usual.

It is important to drink at least 2 litres (3½ pints) of non-alcoholic fluid each day to help protect your kidneys.

Skin cancer risk

This treatment can increase your risk of developing skin cancer. Your doctor or nurse can explain this. Treating the colorectal cancer will usually outweigh the risk of this. Your doctor may check your skin. Tell your doctor or nurse straightaway about any new skin changes or any changes to a mole.

Less common side effects

Allergic reaction

Some people have an allergic reaction to encorafenib. The symptoms are similar to those we describe in an allergic reaction to cetuximab. If you feel unwell or have any of these signs, contact the hospital straight away.

Effects on the eyes

This treatment can affect your eyes. Always tell your doctor or nurse if you have sore eyes, blurry vision or any sight loss. They may give you eye drops or other treatments to help. They may also arrange a specialist eye check for you. Do not drive if your eyesight is affected.

Effects on the heart

This treatment can affect how the heart works. You may have tests to check how well your heart is working. These may be done before, during and after treatment.

If the treatment is causing heart problems, your doctor may change the type of treatment you are having.

Contact the hospital straight away on the 24-hour number if you have any of these symptoms during or after treatment:

  • breathlessness
  • dizziness
  • changes to your heartbeat
  • swollen feet and ankles.

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

Always call 999 if you have:

  • chest pain, pressure, heaviness, tightness or squeezing across the chest
  • difficulty breathing.

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.

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 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 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.