Avelumab (Bavencio)

Avelumab (also known as Bavencio) is a type of immunotherapy. You might have it as a treatment for:

  • merkel cell carcinoma (MCC) that has spread to other parts of the body 
  • a type of kidney cancer called renal cell cancer that has spread, you have it with another cancer drug called axitinib
  • advanced urothelial cancers if you have had chemotherapy and your cancer hasn’t grown

Urothelial cancers include cancers of the:

  • bladder
  • ureters - the tubes that carry the urine from the kidneys to the bladder
  • urethra - the tube that carries the urine from your bladder out of your body

How does avelumab work?

Avelumab is a type of immunotherapy called a checkpoint inhibitor. It blocks proteins that stop the immune system from attacking the cancer cells. This allows the immune cells to kill the cancer cells. 

How do you have avelumab?

You have avelumab as a drip into your bloodstream (intravenously). It takes about an hour each time you have it.

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

Or you might have it through a long line: a central line, a PICC line or a portacath.

These are long plastic tubes that give the drug into a large vein in your chest. The tube stays in place throughout the course of treatment.

How often do you have avelumab?

You have avelumab every 2 weeks. You have it for as long as it helps you and the side effects aren’t too bad.

You might have paracetamol and an anti histamine drug before at least the first 4 avelumab treatments. This reduces your risk of having an allergic reaction during treatment.


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, thyroid and kidneys are working.

What are the side effects of avelumab?

Side effects can vary from person to person. They also depend on what other treatment you are having. 

This treatment affects the immune system. This may cause inflammation in different parts of the body which can cause serious side effects. They could happen during treatment, or some months after treatment has finished. In some people, these side effects could be life threatening.

When to contact your team

Your doctor, pharmacist or nurse will go through the possible side effects. They will monitor you closely 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 healthcare team 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 effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:

A reaction during the infusion

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.

Diarrhoea and inflamed bowel

Tell your doctor or nurse if you have diarrhoea. Your doctor might give you anti diarrhoea medicine to take home with you after treatment. Eat less fibre, avoid raw fruits, fruit juice, cereals and vegetables, and drink plenty of liquid to replace the fluid lost.

Call your advice line straight away if you have 4 loose watery poos (stools) in 24 hours, diarrhoea at night, or it carries on for more than 3 days. Or if you can’t drink enough to replace the lost fluid. Also, call if you have blood or mucus in your poo, your poo looks darker than usual, or if you develop pain in your tummy (abdomen).


Tiredness and weakness (fatigue) can happen during and after treatment. Doing gentle exercises each day can keep your energy up. Don't push yourself, rest when you start to feel tired and ask others for help.

Let your doctor know if you are more tired than usual.

Loss of appetite and weight loss

You might not feel like eating and may lose weight. Eating several small meals and snacks throughout the day can be easier to manage. You can talk to a dietitian if you are concerned about your appetite or weight loss. 

Difficulty breathing and cough

You may have difficulty breathing or a cough. Let your doctor or nurse know straight away if you have these symptoms. They can give you medicine to help.

Breathlessness and looking pale

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

Feeling or being sick

Feeling sick is usually mild. Anti sickness tablets can control it if you need them. Tell your doctor or nurse if you feel sick. 

Tummy (abdominal) pain

Tell your treatment team if you have this. They can check the cause and give you medicine to help. 

Pain in your back or joints

Let your doctor know if you have pain in your back or joints. There are lots of ways to treat pain, including painkillers and relaxation.


Constipation Open a glossary item is easier to sort out if you treat it early. Drink plenty and eat as much fresh fruit and vegetables as you can. Try to take gentle exercise, such as walking. Tell your healthcare team if you think you are constipated. They can give you a laxative if needed.

High temperature

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.

Swollen hands and feet

Swelling of hands and feet is due to fluid build up. This is called oedema. Let your doctor or nurse know if you have any swelling.

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:

  • low levels of white blood cells in your body which can increase your risk of getting an infection
  • a drop in the levels of platelets in your body which can increase your risk of bruising, bleeding and nosebleeds
  • headaches and dizziness - tell your doctor or nurse if you have these symptoms
  • numbness and tingling in fingers and toes which can make it difficult doing up buttons
  • changes to the levels of thyroid hormones in your body - low levels can make you feel tired and cold, high levels can cause other symptoms including heart palpitations
  • high or low blood pressure
  • inflammation of the lung tissue (pneumonitis)
  • dry mouth
  • skin changes such as a rash, itching and dry skin
  • pain in your muscles
  • flu like symptoms such as shivering, chills and feeling generally unwell
  • higher levels of liver and pancreatic enzymes that are usually temporary and go back to normal once you stop treatment
  • inflammation of your joints
  • muscle weakness (Myasthenia gravis)

Rare side effects

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

  • high blood sugar levels (diabetes)
  • inflammation in different parts of your body such as the heart, thyroid, eyes, bowel, liver and kidneys - you may need to take steroids or other treatments to help manage these side effects
  • problems with your nerves that can cause numbness, weakness and pain
  • low levels of different hormones in your body

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

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 Open a glossary item 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 drug may harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you are having treatment with this drug and for at least a month afterwards.

Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if you or your partner become pregnant while having treatment.


It is not known whether this drug comes through into the breast milk. Doctors usually advise that you don’t breastfeed during this treatment.

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.

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