Bevacizumab (Avastin)

What is bevacizumab?

Bevacizumab, also known as Avastin, is a targeted therapy and belongs to a group of cancer drugs known as monoclonal antibodies. Bevacizumab is used to treat secondary breast cancer (also known as advanced or metastatic breast cancer).

It’s usually given in combination with chemotherapy drugs such as paclitaxel, docetaxel or capecitabine. You may continue to have bevacizumab after the course of chemotherapy has finished for as long as it’s keeping the cancer under control.

How does bevacizumab work?

For cancers to grow and spread, they need a constant supply of oxygen and other nutrients. Cancers can improve their access to these by developing their own blood supply. This process is called angiogenesis. You can find out more about blood supply and how cancers grow on the Cancer Research UK website.

Bevacizumab is an angiogenesis inhibitor. It works by targeting a protein called vascular endothelial growth factor (VEGF) that helps cancers form new blood vessels.

By stopping this process, bevacizumab ‘suffocates’ the blood supply to the cancer, shrinking it and stopping it from growing.

Who might be offered bevacizumab?

Bevacizumab is not routinely offered on the NHS. However, you may be given it as part of a clinical trial. Your specialist will be able to tell you if this is an option for you.

How is bevacizumab given?

Bevacizumab is a colourless fluid given into a vein (intravenously). If it's difficult to find a vein, a central venous access device such as a skin-tunnelled catheter may be used. Find out more about central venous devices.

The first dose is given over about 90 minutes. Future doses can be given over 30–60 minutes as long as you don’t feel unwell while it’s being given.

You’ll have bevacizumab as an outpatient every two or three weeks for as long as your specialist team feels you’re benefiting from the drug and you’re coping with any side effects.

What are the side effects of bevacizumab?

Like any drug, bevacizumab can cause side effects. However, everyone reacts differently to drugs and some people have more side effects than others. You may not have all or any of these.

If you are having bevacizumab alongside chemotherapy, you may also have side effects from the chemotherapy. If you’re concerned about any problems or side effects, regardless of whether they’re listed here, talk to your specialist team as they may be able to help.

Common side effects

High blood pressure (hypertension)

Bevacizumab can cause high blood pressure. Your blood pressure should be checked each time you’re given bevacizumab to ensure it’s not too high. If you have severe headaches, nose bleeds or if you feel dizzy, let your GP (local doctor) or your specialist team know. You may be prescribed tablets to lower your blood pressure.

Loss of appetite or nausea (feeling sick)

You may not feel like eating and/or you may feel sick at times during your treatment, although most people will not actually be sick. Anti-sickness tablets can help. Try to eat small, regular meals if possible and have regular drinks.

Diarrhoea or constipation

Tell your GP or specialist team if you have diarrhoea during treatment as they can prescribe drugs to control it. It’s especially important to tell them if you’ve had more than four episodes of diarrhoea in a 24-hour period. Try to drink plenty of fluids to avoid being dehydrated.

Drinking plenty of fluids every day will also help with constipation. Try eating foods that contain fibre (such as fruit, vegetables and wholemeal bread) and doing some regular, gentle exercise.


Fatigue is extreme tiredness that doesn’t go away with rest or sleep. It’s a very common side effect of breast cancer treatment and may affect you physically and emotionally. Tell your GP or specialist team about your fatigue so you can be fully assessed and offered advice on how to manage your energy levels.

Find out more about managing fatigue with secondary breast cancer.

Risk of infection

Bevacizumab can cause a drop in white blood cells which can increase the risk of getting an infection. The number of blood cells usually returns to normal before your next course of treatment is due. When white blood cells fall below a certain level, it’s known as neutropenia. If you feel unwell, are shivering or have a temperature (above 38°C), it’s known as febrile neutropenia.

If you feel unwell, develop a sore throat or shivering or have a temperature above 38 degrees Celsius at any time during your treatment, you should contact the hospital immediately, even if this happens at the weekend or during the night. You may need to be treated with antibiotics or other drugs that help produce more white blood cells.

Anaemia (a drop in red blood cells)

If the number of red blood cells is low, you may be tired or breathless. Tell your GP or specialist team if you feel like this.

Other common side effects may include:

  • joint and muscle pain
  • numb and tingling feet (peripheral neuropathy)
  • eye problems
  • voice changes (croaky, hoarse).

Less common side effects

Allergic reaction

If you have an allergic reaction to bevacizumab, it will probably happen within the first few hours after your treatment and will most likely be the first or second time you have the drug. Reactions can vary from mild to severe, but severe reactions are uncommon.

You’ll be monitored closely during your treatment so that any reaction can be dealt with immediately. Symptoms of an allergic reaction include flushing, skin rash, itchiness, back pain, shortness of breath, faintness, fever or chills. If you have a severe reaction, treatment will be stopped immediately.

Occasionally these symptoms start later than six hours after your treatment. If this happens contact the hospital immediately.

Heart problems

Bevacizumab can cause heart problems. If you have any symptoms such as chest pain, difficulty breathing, feeling like your heart is beating very fast or swollen ankles tell your specialist team straight away.

Kidney problems

Bevacizumab can cause protein in the urine. This will be tested regularly throughout your treatment. If it’s found, you’ll be asked for a 24-hour collection of urine to make sure your kidneys are working normally.

Increased risk of bleeding

For example, your gums may bleed, you may bruise very easily or you may get nose bleeds. Tell your GP or specialist team if you notice any bleeding.

Rarer side effects


People having bevacizumab are at a very slightly higher risk of having a stroke. If you develop weakness in your arms or legs, drooping on one side of your face or difficulty talking, contact your local Accident and Emergency (A&E) department or a doctor or nurse from your specialist team straight away.

Heart attack

In very rare cases, having bevacizumab can lead to a heart attack. If you have any symptoms of a heart attack such as chest pain, dizziness, shortness of breath, feeling sick (nausea) or being sick (vomiting), contact your local A&E department or a doctor or nurse from your specialist team straight away.

Bowel perforation

A very small number of people develop a small hole (perforation) in their bowel. If you develop sudden, severe pain in your tummy (abdomen), contact your local A&E department or a doctor or nurse from your specialist team straight away.


A fistula is the development of a small tunnel-like connection between two organs that are not normally connected. If you notice any changes in your bowel or bladder habits, or any vaginal changes that are not normal for you, contact a doctor or nurse from your specialist team straight away.

Osteonecrosis of the jaw (when bone in the jaw dies)

This is a rare side effect, but is more common in patients who are also having treatment with a bisphosphonate (such as zoledronic acid (Zometa)) or with denosumab (Xvega).

Good dental hygiene reduces the risk. It’s important to discuss any dental problems with your specialist before starting bevacizumab and to let your dentist know you are having it if you need any dental treatment.

PRES (posterior encephalopathy syndrome)

A condition called PRES can very occasionally occur, usually due to very high blood pressure. If you notice changes in your vision, headaches, confusion or seizures (fits) contact your local A&E department or a doctor or nurse from your specialist team straight away.

Slow wound healing

If you have any problems with wounds not healing, speak to your specialist team straight away. You may have to stop taking bevacizumab for a short while to allow them to heal.

Other issues

Blood clots

People with breast cancer have a higher risk of blood clots because of the cancer itself and some treatments for breast cancer. Having bevacizumab increases the risk of blood clots such as deep vein thrombosis (DVT). People with a DVT are at risk of developing a pulmonary embolism. This is when part of the blood clot breaks away and travels to the lung.

If the cancer has spread to other parts of the body this also increases the risk.

Blood clots can be harmful but are treatable so it’s important to report symptoms quickly.

If you experience any of the following symptoms contact your local A&E department, or specialist team straight away.

  • Pain, redness/discolouration, heat and swelling of the calf, leg or thigh.
  • Swelling, redness or tenderness where a central line is inserted to give chemotherapy, for example in the arm, chest area or up into the neck.
  • Shortness of breath.
  • Tightness in the chest.
  • Unexplained cough (may cough up blood).

Find out more about blood clots.


It’s important you don’t get pregnant while you’re having bevacizumab as it can harm a developing baby. 


It’s possible for bevacizumab to be present in breast milk, so women should not breast feed while having treatment or for six months afterwards.


Live vaccines, such as the MMR, BCG and yellow fever vaccines, should not be given while you’re on this treatment, or for six months afterwards.

It’s safe to be in contact with people who have been given a live vaccine by injection, but be cautious with people who have been given oral vaccines (given by mouth) as these can be transferred from person to person. These include vaccines for polio, cholera, typhoid and rotavirus.

You can have other vaccines, but they may not give you as much protection as usual until your immune system has fully recovered from your treatment. It is safe to have the flu vaccine.

Other medicines

Talk to your specialist or pharmacist if you are taking any other prescribed or over the counter medicines as these may interact with bevacizumab. You should also discuss any complementary therapies, herbal remedies or supplements you may wish to use before you start them.

Last reviewed: 2017
Next planned review begins 2019

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