Cancer drugs A to Z list
Lonsurf is a treatment for:
bowel cancer that has spread from where is started to other parts of the body. This is called advanced or metastatic cancer
stomach (gastric) cancer that has spread to other parts of the body
advanced of the
Find out more about your cancer type
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 in the body by stopping it from being broken down.
You might have Lonsurf in combination with bevacizumab.
Read more about how chemotherapy works
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.
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 a cancer drug or if you miss a dose.
You take Lonsurf in . This means you have the drug and then a rest to allow your body to recover.
Each cycle of treatment lasts 28 days (4 weeks).
You have a cycle of treatment in the following way:
Days 1 to 5 – you take Lonsurf twice a day.
Days 6 to 7 – you don't take any treatment.
Days 8 to 12 – you take Lonsurf twice a day.
Days 13 to 14 – you don't take any treatment.
Days 15 to 28 - you don't take any treatment.
Then you start your next cycle of treatment.
You usually take Lonsurf for as long as it is working and the side effects aren't too bad.
You have blood tests before and during your treatment. They check your levels of and other substances in the blood. They also check how well your liver and kidneys are working.
Before treatment starts you may have a blood test to check for viruses such as hepatitis B, hepatitis C, and HIV. This is called a viral screen.
It’s important for your doctor to know if you have had any of these viruses. This is because this treatment can weaken your and can cause the virus to become active again (reactivation).
Side effects can vary from person to person. They also depend on what other treatments you're having.
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.
We haven't listed all the side effects here. Talk to your healthcare team if you have any new symptoms that you think might be a side effect of your treatment.
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.
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 is due to a drop in . Symptoms include a change in temperature, aching muscles, cough, headaches, feeling cold and shivery, pain or a burning feeling when peeing or generally feeling 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.
Rarely, you may get a fungal or yeast infection, such as athlete's foot, which causes itchy dry skin between the toes.
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. This is known as petechiae.
You might be breathless and look pale due to a drop in . This is called anaemia.
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 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.
You may have some dry heaving or retching, but this is rare.
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.
Contact your advice line if you have diarrhoea. For example, in one day you have 2 or more loose bowel movements than usual. If you have a , you might have more output than normal. Your doctor may give you anti diarrhoea medicine to take home with you after treatment.
Try to eat small meals and snacks regularly. It’s best to try to have a healthy balanced diet if you can. You don’t necessarily need to stop eating foods that contain . But if your diet is normally very high in fibre, it might help to cut back on high fibre foods such as beans, nuts, seeds, dried fruit, bran and raw vegetables.
Drink plenty to try and replace the fluid lost. Aim for 8 to 10 glasses per day.
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:
chest infection
swelling of your hands and legs due to a build up of fluid (oedema)
constipation – drink plenty and eat foods high in fibre. Your nurse can give you laxatives to help if needed
changes to your taste
feeling generally unwell (malaise)
liver changes picked up on blood tests, it may cause yellowing of the skin or eyes (jaundice). These changes are sometimes severe, but this is rare
high temperature (fever)
sore mouth or ulcers, and inflammation in your stomach lining
protein in your urine – your nurse tests your urine before and during treatment
shortness of breath - tell your doctor if you have any shortness of breath
skin problems such as a rash, dry, itchy or flaky skin – talk to your team about any changes to your skin
tummy (abdominal) pain
low levels of albumin in your body that can cause swelling and weakness in your legs, ankles and abdomen
hair loss – this is usually temporary and grows back after treatment finishes
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
sepsis is a serious reaction to an infection - signs can include feeling very unwell, not passing urine, a very high or very low temperature, shivering, slurred speech or confusion, breathlessness, mottled or discoloured skin, extreme shivering or muscle pain. Call 999 or go to accident and emergency (A&E) immediately if you have any of these symptoms
infection in the or
eye infection (conjunctivitis) - your eyes may feel gritty, itchy, sticky from pus, watery and look red
that affects the nerves
influenza (the flu)
an infection causing a runny nose and sore throat, such as the common cold
problems with staying of falling asleep (insomnia)
feeling dizzy or the feeling of the room spinning or moving around you (vertigo)
headache
lack of fluid in the body (dehydration - signs include feeling dizzy, not passing enough pee (urine) and dark coloured urine
high blood sugar levels that can cause headaches, feeling thirsty and blurred vision
pain, numbness or tingling, usually in your fingers or toes (peripheral neuropathy) - it is often temporary and can improve after you finish treatment
temporary feeling of tingling, burning or numbness, also called "pins and needles"
changes in memory, concentration and ability to think clearly
the skin on your face, neck and chest looking red (flushed)
a cough or hoarse, raspy voice
red and swollen tongue
inflammation or bleeding in your digestive tract, which includes your mouth, throat, stomach, intestines, anus and rectum
your bowel becoming slow, sluggish and not working properly
indigestion, acid reflux and passing more wind than usual
tooth or nail problems
redness, swelling and pain on the palms of your hands or soles of your feet
spots (acne)
sweating more than usual
changes in blood pressure - it may be higher or lower than usual
pain, including in your arms and legs, muscles, joints, bones or from the cancer
muscle weakness and spasms
anxiety
changes to the levels of minerals and salts in your blood, including high or low levels of potassium and low levels of calcium, sodium and phosphate. You have regular blood tests during treatment to check for these
changes in levels of proteins in the blood to check for inflammation
changes to blood clotting found in blood tests
changes in the way your kidneys work causing problems such as kidney failure
blood in your urine or problems passing urine and loss of bladder control
changes in heart rhythm or palpitations
chest pain (angina). Go to A&E or call 999 as soon as possible if you have chest pain
nosebleeds
abdominal bloating
feeling like your body temperature has changed
We have more information about side effects and tips on how to cope with them.
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.
It is not known whether this treatment affects in people. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.
This treatment may harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you're having treatment and for at least 6 months 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.
Don’t breastfeed during this treatment because the drug may come through into your breast milk.
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, and yellow fever.
You can usually 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 a vaccine in relation to your cancer treatment.
You can be in contact with other people who have had live vaccines as injections. If someone has had a live vaccine by mouth or nasal spray there may be a small risk the vaccine virus can be passed onto you if your is weakened.
Your healthcare team will let you know if you need to take any precautions if you are in close contact with someone who has had a live vaccine.
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 and Healthcare products Regulatory Agency (MHRA) as part of their Yellow Card Scheme.
Last reviewed: 19 May 2026
Next review due: 19 May 2029
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