Obinutuzumab (Gazyvaro)

Obinutuzumab is a type of targeted cancer drug. It is also known as Gazyvaro. 

It is a treatment for chronic lymphocytic leukaemia (CLL) and follicular lymphoma. 

You pronounce obintuzumab as Oh-bin-you-too-zoo-mab.

How does obinutuzumab work?

Obinutuzumab is a type of targeted cancer drug called a monoclonal antibody.

Monoclonal antibodies work by recognising and finding specific proteins on cells.

Obinutuzumab targets a protein called CD20 on the surface of the lymphoma and leukaemia cells. Obinutuzumab sticks to all the CD20 proteins it finds. This makes it easier for the cells of the immune system to pick out the marked cells and kill them. 

How do you have obinutuzumab?

You have obinutuzumab as a drip into your bloodstream (intravenously). You usually have it with other cancer drugs (as part of a treatment regimen). 

You might have treatment through a long plastic tube that goes into a large vein in your chest. The tube stays in place throughout the course of treatment. This can be a:

  • central line
  • PICC line
  • portacath

If you don't have a central line

You might have treatment through a thin short tube (a cannula) that goes into a vein in your arm. You have a new cannula each time you have treatment.

When do you have obinutuzumab?

You have obinutuzumab as cycles of treatment. This means that you have the drug then a rest to allow your body to recover. Each cycle varies depending on what type of cancer you have.

Obinutuzumab can cause an allergic reaction. Before treatment, you will be given medicines to help prevent or reduce any reaction.

You usually have up to 6 cycles of treatment in total, in combination with other cancer drugs. 

Cycle 1

You have obinutuzumab on day 1, 8, and 15. On day 1 obinutuzumab is given very slowly. You will be monitored carefully to check for any reactions. If you have a reaction, you will be given the rest of your dose the following day (day 2).

Cycle 2 onwards

You have obinutuzumab on day 1.

Your doctor or nurse will tell you more about your treatment plan. It can vary according to your type of cancer and also the other chemotherapy drugs you are prescribed. 

Maintenance treatment for follicular lymphoma

If you have follicular lymphoma, you might then have obinutuzumab on its own every 2 months for up to 2 years. This is called maintenance treatment. It aims to stop the lymphoma coming back for as long as possible.

Your doctor or nurse will tell you more about your treatment plan. 


You have blood tests before and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.

What are the side effects of obinutuzumab?

Side effects can vary from person to person. They also depend on what other treatments you're having. 

When to contact your team

Your doctor, nurse or pharmacist will go through the possible side effects. They will monitor you during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:

  • you have severe side effects 

  • your side effects aren’t getting any better

  • your side effects are getting worse

Early treatment can help manage side effects better. 

Contact your advice line immediately if you have signs of infection, including a temperature above 37.5C or below 36C.

We haven't listed all the side effects here. Remember it is very unlikely that you will have all of these side effects. But you might have some of them at the same time.

Common side effects

These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:

Risk of infection

Increased risk of getting an infection is due to a drop in white blood cells. Symptoms include a change in temperature, aching muscles, headaches, feeling cold and shivery and generally unwell. You might have other symptoms depending on where the infection is.

Infections can sometimes be life threatening. You should contact your advice line urgently if you think you have an infection. 

Bruising and bleeding

This is due to a drop in the number of platelets in your blood. These blood cells help the blood to clot when we cut ourselves. You may have nosebleeds or bleeding gums after brushing your teeth. Or you may have lots of tiny red spots or bruises on your arms or legs (known as petechiae).

Breathlessness and looking pale

You might be breathless and look pale due to a drop in red blood cells. This is called anaemia.

Lung problems

You might develop a cough or breathing problems. This could be due to infection, such as pneumonia or inflammation of the lungs. 

Let your doctor or nurse know straight away if you suddenly become breathless or develop a cough.

Inflammation in the nose

You might have a blocked nose, painful sinuses, and a sore throat. 


You might have to take an anti viral drug to prevent shingles (herpes zoster virus).

Problems passing urine

You might find it difficult to pass urine, want to go with some urgency or are going more often. There may be pain or burning when you go. You may see blood in your urine, or your urine might smell bad or look cloudy. This could be due to a urinary tract infection (UTI).

Tell your doctor or nurse if you think you might have a UTI. They can give you medicine to help.

Difficulty sleeping

If you have difficulty sleeping, it can help to change a few things about how you try to sleep. Try to go to bed and get up at the same time each day and spend some time relaxing before you go to bed. Some light exercise each day may also help. 


Tell your healthcare team if you keep getting headaches. They can give you painkillers to help.

Diarrhoea or constipation

Tell your healthcare team if you have diarrhoea or constipation. They can give you medicine to help. 

Hair loss (alopecia)

If you are having obinutuzumab in combination with chemotherapy you could lose some or all of your your hair. This is likely to be due to the chemotherapy that obinutuzumab is used with. This includes your eyelashes, eyebrows, underarms, legs and sometimes pubic hair. Your hair will usually grow back once treatment has finished but it is likely to be softer. It may grow back a different colour or be curlier than before. 


You might have itching (pruritus). Let your doctor or nurse know if you have this.  

Joint or muscle pain

You might feel some pain from your muscles and joints. Speak to your doctor or nurse about what painkillers you can take to help with this.

Tiredness and weakness

You might feel very tired and as though you lack energy.

Various things can help you to reduce tiredness and cope with it, for example exercise. Some research has shown that taking gentle exercise can give you more energy. It is important to balance exercise with resting.

High temperature (fever)

If you get a high temperature, let your healthcare team know straight away. Ask them if you can take paracetamol to help lower your temperature.

Allergic reaction

A reaction may happen during the infusion. Symptoms can include a skin rash, itching, swelling of the lips, face or throat, breathing difficulties, fever and chills. Your nurse will give you medicines beforehand to try to prevent a reaction. 

Tell your doctor or nurse immediately if at any time you feel unwell. They will slow or stop your drip for a while and give you medicine to help relieve your symptoms.

Occasional side effects

These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include:

  • a runny or blocked nose
  • cold sores
  • getting a type of skin cancer called squamous cell carcinoma or basal cell carcinoma
  • high uric acid levels in the blood due to the breakdown of tumour cells (tumour lysis syndrome)
  • changes in potassium levels in the blood
  • feeling anxious and depressed
  • chest pain
  • heart problems such as cardiac failure and an irregular and fast heart beat causing shortness of breath and light headedness
  • high blood pressure which can cause headaches, nose bleeds, blurred or double vision or shortness of breath
  • weight gain
  • night sweats
  • patches of skin becoming inflamed, itchy, red, cracked, and rough (eczema)
  • problems with digestion such as heartburn
  • inflammation of the intestine which can cause pain, diarrhoea, tiredness and weight loss
  • a hole in your bowel or stomach (perforation) which can cause severe tummy pain - contact your doctor straight away if you have this
  • swollen veins in the anus which can be painful and get irritated when you empty your bowels (haemorrhoids)
  • pain in different parts of the body such as your bones, mouth and throat, chest, arms and legs
  • changes in the levels of minerals in your body

Rare side effects

These side effects happens in fewer than 1 in 100 people (fewer than 1%). You might have one or more of them. They include:

  • a serious illness where clots form all over the body (disseminated intravascular coagulation). Contact your doctor straight away if you have bleeding, sudden chest pain or breathlessness
  • if you have had a liver infection in the past called hepatitis B, obinutuzumab can sometimes make it active again. Your healthcare team will talk to you about this

Other side effects

There isn't enough information to work out how often this side effect might happen. A viral infection that can cause damage to areas of the brain called progressive multifocal leukoencephalopathy (PML). Symptoms include confusion, difficulty thinking, memory loss, eyesight changes, weakness, loss of control or sensation in an arm or leg, difficulty walking, or loss of balance. 

This condition can be very serious and even life threatening. Let your doctor or nurse know straight away if you have any of these changes.

Coping with side effects

We have more information about side effects and tips on how to cope with them.

What else do I need to know?

Other medicines, foods and drinks

Other medicines, food and drink

Cancer drugs can interact with medicines, herbal products, and some food and drinks. We are unable to list all the possible interactions that may happen. An example is grapefruit or grapefruit juice which can increase the side effects of certain drugs.

Tell your healthcare team about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies. Also let them know about any other medical conditions or allergies you may have.

Loss of fertility

It is not known whether this treatment affects fertility in people. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.

Contraception and pregnancy

This treatment might harm a baby developing in the womb. It is important not to become pregnant while you're having treatment and for at least 18 months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.

Continue to use effective contraception for 18 months after stopping treatment with obinutuzumab.


Don’t breastfeed during this treatment and for 18 months afterwards. The drug may come through in the breast milk.

Treatment for other conditions

If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.


Don’t have immunisations with live vaccines while you’re having treatment and for up to 12 months afterwards. The length of time depends on the treatment you are having. Ask your doctor or pharmacist how long you should avoid live vaccinations.

In the UK, live vaccines include rubella, mumps, measles, BCG, yellow fever and one of the shingles vaccines called Zostavax.

You can have:

  • other vaccines, but they might not give you as much protection as usual
  • the flu vaccine (as an injection)
  • the coronavirus (COVID-19) vaccine - talk to your doctor or pharmacist about the best time to have it in relation to your cancer treatment

Members of your household who are aged 5 years or over are also able to have the COVID-19 vaccine. This is to help lower your risk of getting COVID-19 while having cancer treatment and until your immune system Open a glossary item recovers from treatment.

Contact with others who have had immunisations - You can be in contact with other people who have had live vaccines as injections. Avoid close contact with people who have recently had live vaccines taken by mouth (oral vaccines) such as the oral typhoid vaccine. Sometimes people who have had the live shingles vaccine can get a shingles type rash. If this happens they should keep the area covered.

If your immune system is severely weakened, you should avoid contact with children who have had the flu vaccine as a nasal spray as this is a live vaccine. This is for 2 weeks following their vaccination.

Babies have the live rotavirus vaccine. The virus is in the baby’s poo for about 2 weeks and could make you ill if your immunity is low. Get someone else to change their nappies during this time if you can. If this isn't possible, wash your hands well after changing their nappy.

More information about this treatment

For further information about this treatment and possible side effects go to the electronic Medicines Compendium (eMC) website. You can find the patient information leaflet on this website.

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.

  • Electronic medicines compendium 
    Accessed November 2023

  • Obinutuzumab with bendamustine for treating follicular lymphoma after rituximab Technology appraisal guidance (TA629)
    National Institute for Health and Care Excellence, 2020

  • Obinutuzumab for untreated advanced follicular lymphoma Technology appraisal guidance (TA513)
    National Institute for Health and Care Excellence 2018

  • Obinutuzumab with bendamustine for treating follicular lymphoma refractory to rituximab Technology appraisal guidance (TA472)
    National Institute for Health and Care Excellence 2017 

  • Obinutuzumab in combinaion with chlorambucil for untreated chronic lymphocytic leukaemia Technology appraisal (TA343) 
    National Institute for Health and Care Excellence 2015 

  • Immunisation against infectious disease : chapter 6: General contraindications to vaccination
    Public Health England 
    First published: March 2013 and regularly updated on the Gov.UK website

Last reviewed: 
21 Nov 2023
Next review due: 
21 Oct 2026

Related links