Each person's reaction to chemotherapy is different. Some people have very few side effects, while others may experience more. The side effects described in this information will not affect everyone who is given irinotecan, and may be different if you are having more than one chemotherapy drug.
We have outlined the most common side effects as well as some less common ones, so that you can be aware of them if they occur. However, we have not included those which are very rare and therefore extremely unlikely to affect you. If you notice any effects which you think may be due to the drug but which are not listed in this information, please discuss them with your doctor or chemotherapy nurse.
Increased sweating, production of saliva, stomach cramps and diarrhoea This is a particular group of side effects that are known as acute cholinergic syndrome. They happen because irinotecan can cause the cells in the body to release too much of a chemical called acetylcholine. The side effects tend to occur during, or within the first 24 hours after an infusion of irinotecan.
These symptoms can usually be prevented or controlled by a drug called atropine. The atropine is given as an injection under the skin (subcutaneously), which can be repeated if necessary.
Delayed diarrhoea If diarrhoea occurs as a delayed side effect (occurring more than 24 hours after an infusion) it can usually be easily controlled, but may occasionally be severe. If you get diarrhoea and abdominal cramps, start taking the anti-diarrhoea medicine (usually loperamide) that you have been given. You should take these medicines exactly as you have been instructed by the hospital treating you, which may be different from the instructions on any printed leaflets provided by the manufacturer.
Normally your doctor will tell you to take two tablets or capsules to start with and then one every two hours until you have not had a loose bowel movement for 12 hours. If loperamide does not work quickly (certainly if you still have diarrhoea after 48 hours) it is important that you contact the hospital. You may become dehydrated if you have a lot of diarrhoea. In some situations you may be asked to take liquids to re-hydrate you and replace any salts that you have lost. Antibiotics are also sometimes given if diarrhoea occurs.
Feeling sick (nausea) and being sick (vomiting) If you do feel sick this may begin a few hours after the treatment is given and last for up to a day. Your doctor can prescribe very effective anti-sickness (anti-emetic) drugs to prevent, or greatly reduce, nausea and vomiting. If the sickness is not controlled, or continues, tell your doctor; they can prescribe other anti-sickness drugs which may be more effective. Some anti-sickness drugs can cause constipation. Let your doctor or nurse know if this is a problem.
Loss of appetite This is usually mild and may last a day or so. A dietitian or specialist nurse at your hospital can give advice on boosting your appetite, coping with eating difficulties and maintaining weight.
Lowered resistance to infection Irinotecan can reduce the production of white blood cells by the bone marrow, making you more prone to infection. This effect can begin a few days after treatment has been given and your resistance to infection usually reaches its lowest point in the second week after chemotherapy. Your blood cells will then increase steadily and will usually have returned to normal before your next course of chemotherapy is due.
Contact your doctor or the hospital straightaway if:
- your temperature goes above 38ºC (100.5ºF)
- you suddenly feel unwell (even with a normal temperature).
You will have a blood test before having more chemotherapy, to make sure that your cells have recovered. Occasionally it may be necessary to delay your treatment if the number of blood cells (the blood count) is still low.
Bruising or bleeding Irinotecan can reduce the production of platelets (which help the blood to clot). Let your doctor know if you have any unexplained bruising or bleeding, such as nosebleeds, blood spots or rashes on the skin, or bleeding gums.
Anaemia (low number of red blood cells) While having treatment with irinotecan you may become anaemic. This may make you feel tired and breathless. Let your doctor or nurse know if these effects are a problem.
Hair loss This usually starts 3–4 weeks after the first dose of irinotecan, although it may happen earlier. Hair may completely fall out. You may also have thinning and loss of eyelashes, eyebrows and other body hair. Hair loss is temporary and all your hair will grow again once the treatment ends.
Tiredness and a general feeling of weakness It is important to allow yourself plenty of time to rest.
