What is irinotecan?

Irinotecan is used to treat colon cancer and rectal cancer. It may sometimes be used to treat other cancers. It is best to read this information with our general information about chemotherapy and the type of cancer you have.

Your doctor will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.

How is irinotecan given?

You will be given irinotecan in the chemotherapy day unit or during a stay in hospital. A chemotherapy nurse will give it to you. Irinotecan can be given in combination with other cancer drugs.

During treatment you usually see a cancer doctor, a chemotherapy nurse or a specialist nurse, and a specialist pharmacist. This is who we mean when we mention doctor, nurse or pharmacist in this information.

Before or on the day of treatment, a nurse or person trained to take blood (phlebotomist) will take a blood sample from you. This is to check that your blood cells are at a safe level to have chemotherapy.

You will see a doctor or nurse before you have chemotherapy. They will ask you how you have been feeling. If your blood results are okay, the pharmacist will prepare your chemotherapy. Your nurse will tell you when your treatment is likely to be ready.

Your nurse usually gives you anti-sickness (anti-emetic) drugs before the chemotherapy. The chemotherapy drugs can be given through:

  • a short thin tube the nurse puts into a vein in your arm or hand (cannula)
  • a fine tube that goes under the skin of your chest and into a vein close by (central line)
  • a fine tube that is put into a vein in your arm and goes up into a vein in your chest (PICC line).

Your course of chemotherapy

Irinotecan is usually given in treatment cycles lasting 3 weeks. Each treatment cycle includes days you are given treatment and rest periods from treatment. You usually have a course of several cycles of treatment over a few months. Your nurse or doctor will discuss your treatment plan with you.

About side effects

We explain the most common side effects of this treatment here. We also include some less common side effects.

You may get some of the side effects we mention, but you are unlikely to get all of them. If you are also having treatment with other cancer drugs, you may have some side effects that we haven’t listed here. Always tell your doctor, nurse or pharmacist about any side effects you have.

Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist explains. This means they will be more likely to work for you. Your nurse will give you advice about managing your side effects. After your treatment is over, most side effects start to improve.

Serious and life-threatening side effects

Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.

Contact the hospital

Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. 

Save these numbers in your phone or keep them somewhere safe.

More information

We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.

Side effects while treatment is being given

Irinotecan reaction (acute cholinergic syndrome)

Some people may have side effects within 24 hours of having irinotecan. These include:

  • diarrhoea
  • tummy cramps
  • sweating more than usual
  • producing a lot of saliva.

This is called acute cholinergic syndrome.

It can usually be prevented or controlled by a drug called atropine. Your nurse gives you atropine as an injection under the skin (subcutaneously). Contact your doctor or nurse if you have any of these symptoms.

Common side effects

Risk of infection

This treatment can reduce the number of white blood cells in your blood. These cells fight infection.

If the number of white blood cells is low, you are more likely to get an infection. A low white blood cell count is called neutropenia.

If you have an infection, it is important to treat it as soon as possible.

Contact the hospital straight away on the 24-hour contact number you have if:

  • your temperature goes over 37.5°C (99.5°F)
  • you suddenly feel unwell, even with a normal temperature
  • you have symptoms of an infection.

Symptoms of an infection include:

  • feeling shivery
  • a sore throat
  • a cough
  • diarrhoea
  • needing to pass urine often.

It is important to follow any specific advice your cancer treatment team gives you.

The number of white blood cells will usually return to normal before your next treatment.

You will have a blood test before having more treatment. If your white blood cell count is low, your doctor may delay your treatment for a short time.

Bruising and bleeding

This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot. 

Tell your doctor if you have any bruising or bleeding that you cannot explain. 

This includes:

  • nosebleeds
  • bleeding gums
  • tiny red or purple spots on the skin that may look like a rash.

Some people may need a drip to give them extra platelets. This is called a platelet transfusion.

Anaemia (low number of red blood cells)

This treatment can reduce the number of red blood cells in your blood. These cells carry oxygen around the body.

If the number of red blood cells is low, you may be tired and breathless. Tell your doctor or nurse if you feel like this.

If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.

Diarrhoea

This treatment may cause severe diarrhoea. Your doctor or nurse will give you different advice depending on when the diarrhoea starts.

Diarrhoea that starts less than 24 hours after your treatment

If you have diarrhoea less than 24 hours after your treatment, contact the hospital straight away. You will need treatment. There is more information about this in the section on irinotecan reactions (acute cholinergic syndrome) above.

Diarrhoea that starts 24 hours or more after your treatment

Your doctor or nurse will give you anti-diarrhoea drugs to take at home. If you have diarrhoea that starts 24 hours or more after your treatment, it is important to follow the advice you have been given by your doctor or nurse:

  • Take your anti-diarrhoea drugs exactly as your doctor or nurse told you. They may tell you to take them in a different way to the instructions on the leaflet inside the packet. It is important you follow the instructions you have been given.
  • Drink at least 2 litres (3½ pints) of fluids each day.
  • Avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods.

Contact the hospital straight away if:

  • the anti-diarrhoea drugs do not start to work within 24 hours
  • your temperature is over 37.5°C (99.5°F)
  • you are also feeling or being sick.

Some people may need to go to hospital to have fluids through a drip. You may need to take antibiotics.

Constipation

This treatment can cause constipation. Here are some tips that may help:

  • Drink at least 2 litres (3½ pints) of fluids each day.
  • Eat high-fibre foods, such as fruit, vegetables and wholemeal bread.
  • Do regular gentle exercise, like going for short walks.

If you have constipation, contact the hospital for advice. Your doctor can give you drugs called laxatives to help.

Tummy pain

You may get pain or discomfort in your tummy (abdomen), feel bloated or have indigestion or wind. Your doctor can give you drugs to help improve these symptoms. Tell them if the pain doesn’t improve or if it gets worse.

Feeling sick

You may feel sick in the first few days after this treatment. Your doctor will give you anti-sickness drugs to help prevent or control sickness. Take the drugs exactly as your nurse or pharmacist tells you.

It is easier to prevent sickness than to treat it after it has started.

If you feel sick, take small sips of fluids and eat small amounts often.

If you continue to feel sick, or if you vomit more than once in 24 hours, contact the hospital as soon as possible. They will give you advice and may change the anti-sickness drug to one that works better for you.

Sore mouth

You may get a sore mouth or mouth ulcers. This can make you more likely to get a mouth infection.

Use a soft toothbrush to clean your teeth or dentures in the morning, at night and after meals.

If your mouth is sore:

  • tell your nurse or doctor – they can give you a mouthwash or medicines to help
  • try to drink plenty of fluids
  • avoid alcohol, tobacco, and foods that irritate your mouth.

Loss of appetite

This treatment can affect your appetite. Do not worry if you do not eat much for a day or two. But if your appetite does not come back after a few days, tell your nurse or dietitian. They will give you advice. They may give you food or drink supplements.

Feeling tired

Feeling tired is a common side effect. It is often worse towards the end of treatment and for some weeks after it has finished. Here are some tips:

  • Try to pace yourself and plan your day so you have time to rest.
  • Gentle exercise, like short walks, can give you more energy.
  • If you feel sleepy, do not drive or operate machinery.

Hair loss

Your hair will get thinner or you may lose all the hair from your head. You may also lose your eyelashes, eyebrows or other body hair. Hair loss usually starts after your first or second treatment.

Your nurse can talk to you about ways to cope with hair loss. There are ways to cover up hair loss if you want to. It is important to cover your head to protect your scalp when you are out in the sun.

Hair loss is almost always temporary and your hair will usually grow back after treatment ends.

Less common side effects

Changes to the way the liver works

Irinotecan may affect the way your liver works. This is usually mild and goes back to normal after treatment. You will have blood tests to check how well your liver is working.

Other information

Blood clot risk

Cancer and some cancer treatments can increase the risk of a blood clot. Symptoms of a blood clot include:

  • pain, redness or swelling in a leg or arm
  • breathlessness
  • chest pain.

If you have any of these symptoms, contact a doctor straight away.

A blood clot is serious, but can be treated with drugs that thin the blood. Your doctor or nurse can give you more information.

Other medicines

Some medicines can affect how this treatment works or be harmful when you are having it. Always tell your cancer doctor about any drugs you are taking or planning to take, such as:

  • medicines you have been prescribed
  • medicines you buy in a shop or chemist
  • vitamins, herbal drugs and complementary therapies.

Tell other doctors, pharmacists or dentists who prescribe or give you medicines that you are having this cancer treatment.

You can visit the electronic Medicines Compendium (eMC) for more detailed information about your treatment.

Vaccines

You should avoid having live vaccines while you are having this treatment and for some time afterwards. Live vaccines include:

  • BCG (tuberculosis)
  • shingles
  • yellow fever
  • liquid typhoid
  • MMR (combined measles, mumps and rubella).

You can talk to your doctor if you have any questions about vaccines.

Contraception

Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment. The drugs may harm a developing baby. It is important to use contraception during your treatment and for a while after treatment finishes. Your doctor, nurse or pharmacist can tell you more about this.

Breastfeeding

Women are advised not to breastfeed while having this treatment and for some time afterwards. This is because the drugs could be passed to the baby through breast milk.

Fertility

Some cancer drugs can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor before you start treatment.

Sex

If you have sex in the first few days after chemotherapy, you need to use a condom. This is to protect your partner in case there is any chemotherapy in semen or vaginal fluids.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses that you are having cancer treatment.

Give them the contact details for your cancer doctor so they can ask for advice.

If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having cancer treatment.

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