Vandetanib (Caprelsa)

Vandetanib is a targeted cancer drug and is also known by its brand name Caprelsa.

It is a treatment for advanced medullary thyroid cancer. This means that the cancer can't be removed by surgery or has spread to other parts of the body.

You might also have it as part of a clinical trial for other types cancer, including other types of thyroid cancer.

How it works

Vandetanib is a type of a cancer growth blocker. It stops signals (chemical messengers) that cancer cells use to divide and grow. 

How you have it

You take vandetanib as tablets. You swallow them whole, with water. It can be with or without food.

You have vandetanib once a day. You can choose the best time to take it. But you should take it at about the same time every day.

Taking your tablets

You must take tablets according to the instructions your doctor or pharmacist gives you.

You should take the right dose, not more or less.

Talk to your healthcare team before you stop taking a cancer drug, or if you miss a dose.

Dissolving vandetanib

You can dissolve the tablets in still water if you find it difficult to swallow. Drop the tablet into half a glass of water without crushing it (don't use any other type of liquid).

Stir until it has dissolved, this may take 10 to 15 minutes. Then drink the liquid straight away. Refill the glass halfway with water and drink it to make sure you have had all the medicine. 

When you forget to take vandetanib

Take it straight away if less than 12 hours have passed. 

Do not take the tablets if it has been more than 12 hours. Take your next tablets at the usual time the next day. 

When you have it

You usually carry on taking vandetanib for as long as it works. 


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.

You might also have tests to check the health of your heart, such as an electrocardiogram (ECG). Ask your doctor which tests you might have. 

Side effects

How often and how severe the side effects are can vary from person to person. They also depend on what other treatment you are having. 

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 advice line, doctor or nurse immediately if you have signs of infection, such as a temperature above 37.5C or below 36C, or if you develop a severe skin reaction. Signs of a severe skin reaction include peeling or blistering of the skin.

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:

Increased risk of getting an infection

Signs of an infection include headaches, aching muscles, a cough, a sore throat, pain passing urine, or feeling cold and shivery. 

Let your doctor or nurse know straight away if you have any of these signs or if your temperature goes above 37.5C.

This drug can reduce the number of white blood cells in the blood. This increases your risk of infections. White blood cells help fight infections.

You have antibiotics if you develop an infection during your treatment. You usually have them as tablets. 

Loss of appetite

You might lose your appetite for various reasons whilst having cancer treatment. Sickness, taste changes or tiredness can put you off food and drinks.

Low levels of calcium in the blood

Low calcium levels in the blood can cause painful muscle spasms, cramps or muscle twitching. You might also get numbness or tingling in your feet, hands or around your mouth.

Headaches and dizziness

Let your doctor or nurse know if you have headaches. They can give you painkillers. Don’t drive or operate machinery if you feel dizzy.

Abnormal sense of touch

This can happen when your skin is touched or not. The sensations can include:

  • numbness and prickling like 'pins and needles'
  • burning 
  • wetness
  • itching
  • electric shock

Changes to your eyesight

You might have blurred vision. This can include mild changes in the eye that can lead to blurred vision. 

Changes to your heart beat (rhythm)

You may have changes to how your heart works. This can cause changes to your heart rhythm. 

Your doctor might ask you to have tests to check your heart, such as an electrocardiogram (ECG).

High blood pressure

Tell your doctor or nurse if you have headaches, nosebleeds, blurred or double vision or shortness of breath. Your nurse will check your blood pressure regularly.

Less common this might be very high blood pressure that could lead to a stroke. 


You might get pain especially in the tummy (abdomen). Contact your advice line or tell your treatment team. 


Contact your advice line if you have diarrhoea, such as if you've had 4 or more loose watery poos (stools) in 24 hours. Or if you can't drink to replace the lost fluid. Or if it carries on for more than 3 days.

Your doctor may 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 to replace the fluid lost.

Feeling or being sick

Feeling or being sick is usually well controlled with anti sickness medicines. Avoiding fatty or fried foods, eating small meals and snacks, drinking plenty of water, and relaxation techniques can all help.

It is important to take anti sickness medicines as prescribed even if you don’t feel sick. It is easier to prevent sickness rather than treating it once it has started.


Contact your doctor or pharmacist if you have indigestion or heartburn. They can prescribe medicines to help.

Increase of skin sensitivity to sunlight

Don’t use sunbeds or sit in the sun. Cover up or use a sun block if you go out in the sun. Remember to put sun cream on your head or wear a hat if you have lost any hair there.

Skin and nail problems

Skin and nail problems include a skin rash, dry skin, itching and darker skin. Your nails may also become brittle, dry, change colour or develop ridges. This usually goes back to normal when you finish treatment.

Protein in your urine and stones in the urine tract 

There might be an increase of protein in your urine. 

You might get small stones (deposits of calcium) in the tubes that allow you to pass urine (urinary tract). Signs can include pain in the side, back or when you pass urine. Contact your advice line or tell your doctor or nurse if you have any of these symptoms. 

Tiredness and weakness (fatigue)

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.

Fluid build up (swelling)

A build up of fluid may cause swelling in your arms, hands, ankles, legs, face and other parts of the body. Contact your healthcare team if this happens to you.

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 decrease in the amounts of hormones your thyroid makes (hypothyroidism)
  • changes to the level of chemicals in your blood - you might have blood tests to check for this
  • not enough fluid in your body (dehydration)
  • anxiety
  • changes to taste
  • lack of energy
  • shaking (tremors)
  • loss of consciousness (black outs)
  • problems with balance
  • eye problems such as seeing halos around lights (halo vision), seeing flashes of light, increased pressure in the eye (glaucoma), conjunctivitis or dry eye
  • stroke or similar conditions where the brain doesn't get enough blood
  • coughing up blood
  • inflammation of the bowel (colitis) that can cause diarrhoea
  • dry, sore mouth
  • problems swallowing
  • constipation
  • inflammation of the lining of the stomach (gastritis) can cause pain, burning or gnawing
  • gallstones
  • soreness, numbness, tingling, redness or peeling of the palms (hand foot syndrome)
  • hair loss
  • problems passing urine such as needing to go urgently and frequently, pain when passing urine
  • kidneys stop working
  • high temperature
  • changes to how well your liver works
  • weight loss

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:

  • build up of fluid around the brain causing pressure on the brain signs include confusion, headaches, being sick, eye problems and stiffness on one side of the body. Contact your advice line or doctor straight away if you have any of these symptoms
  • not getting enough nutrients (malnutrition) caused by not having enough to eat or not being able to eat properly. Contact your advice line or talk to your doctor or nurse if you are having problems with eating
  • muscle spasms
  • fits (seizures)
  • cataracts and not having difficulty focusing when changing from looking at a distance to seeing close up
  • heart problems including heart failure and heart attack
  • difficulty breathing or shortness of breath especially after activities, wheezing and coughing up mucus
  • inflammation of the pancreas, lining of the abdomen (peritonitis)
  • slowing of the gut or bowels that can cause a build up of food or a blockage
  • hole (perforation) of the gut or bowels
  • not being able to control your bowel movements (faecal incontinence)
  • blisters on the skin
  • changes to the colour of your urine
  • not passing any urine
  • wounds not healing properly

What else do I need to know

Other medicines, foods and drink

Cancer drugs can interact with some other medicines and herbal products. Tell your doctor or pharmacist about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.

Pregnancy and contraception

This drug may harm a baby developing in the womb. It is important not to become pregnant or father a child while you are having treatment with this drug and for at least 4 months afterwards.

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

Always tell other doctors, nurses, pharmacists or dentists that you’re having this treatment if you need treatment for anything else, including teeth problems.


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 go to the electronic Medicines Compendium (eMC) website.

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

This page is due for review. We will update this as soon as possible.

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