Trifluridine and tipiracil (Lonsurf)

Lonsurf is a type of chemotherapy drug. You pronounce Lonsurf as lon-sur-f.

It is a treatment for:

  • bowel cancer that has spread to other parts of the body
  • stomach (gastric) cancer that has spread to other parts of the body
  • adenocarcinoma Open a glossary item of the gastroesophageal junction Open a glossary item that has spread to another part of the body

How does Lonsurf work?

Lonsurf is made up of 2 drugs, trifluridine and tipiracil.

Trifluridine works by stopping the growth of cancer cells. Tipiracil helps the trifluridine to work longer by stopping it from being broken down by the body.

How do you have Lonsurf?

You take Lonsurf as tablets. Your doctor will tell you how many tablets to take. You take them twice a day with a glass of water. You need to take them within an hour after your morning and evening meals.

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

Speak to your pharmacist if you have problems swallowing the tablets.

Whether you have a full or an empty stomach can affect how much of a drug gets into your bloodstream.

You should take the right dose, no more or less.

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

How often do you have Lonsurf?

You take Lonsurf in a 4 week cycle of treatment Open a glossary item as shown below.

Week 1
  • Days 1 to 5 – take the tablets twice a day
  • Days 6 to 7 – don’t take the tablets
Week 2
  • Days 8 to 12 – take the tablets twice a day
  • Days 13 to 14 – don’t take the tablets
Weeks 3 and 4
  • Don’t take any of the tablets

Then you start the cycle again.

You usually take Lonsurf for as long as it helps you and the side effects aren't too bad. 


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 Lonsurf?

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:

Increased risk of getting an 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, bleeding gums or nose bleeds (thrombocytopenia)

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 (anaemia)

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

Loss of appetite

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. 

Feeling tired (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.

Feeling or being sick

Feeling or being sick is usually well controlled with anti sickness medicines. It might help to avoid fatty or fried foods, eat small meals and snacks and take regular sips of water. Relaxation techniques might also 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 treat it once it has started.


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.

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:

  • weight loss
  • constipation – drink plenty and eat foods high in fibre. Your nurse can give you laxatives to help if needed
  • changes to your taste
  • feeling dizzy
  • a headache
  • feeling generally unwell (malaise)
  • liver changes picked up on blood tests
  • redness, swelling and pain on the palms of hands or soles of feet
  • numbness or tingling, usually in your fingers or toes
  • sore mouth or ulcers
  • protein in your urine – your nurse tests your urine before and during treatment
  • problems with staying or falling asleep (insomnia)
  • cough or shortness of breath – tell your doctor if you have any shortness of breath
  • skin problems such as a rash, itchy or flaky skin or flushing – talk to your team about any changes to your skin
  • tummy pain
  • low levels of albumin in your body that can cause swelling and weakness
  • hair loss – this is usually temporary and grows back after treatment finishes

Rare side effects

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

  • a blood clot – this can be life threatening. Signs are pain, redness and swelling where the clot is. Feeling breathless or pain in your chest or upper back can be a sign of a blood clot in the lung. Contact your advice line or go to A&E straight away
  • septic shock – this is a life threatening condition it happens after a serious infection. Signs include low blood pressure, high fever, chills, confusion, general pain, fast heartbeat, rapid breathing and a rash. Contact the advice line or see your doctor
  • ear ache
  • indigestion
  • changes in blood pressure – it may be higher or lower than normal
  • eye problems such as changes to your sight, or red, sticky eyes that feel gritty and may water (conjunctivitis) or dry eyes – call your advice line about any eye problems
  • pain, including in your muscles, joints, bones or tumour
  • anxiety
  • changes to your periods (menstrual cycle)
  • changes to the levels of minerals and salts in your body – picked up on blood tests
  • kidney problems including kidney failure
  • passing out or fainting
  • high blood sugar levels
  • problems passing urine or loss of bladder control
  • changes in heart rhythm

Coping with side effects

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

What else do you need to know?

Other medicines, foods 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.

Pregnancy and contraception

This treatment might harm a baby developing in the womb. It is important not to become pregnant or father a child while you are having treatment and for 6 months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.


Don’t breastfeed during this treatment because the drug may come through into your breast milk.


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.

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.

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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