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Irinotecan is used to treat colon cancer. Common side effects include stomach upset, bone marrow suppression, loss of appetite or weight loss, mouth sores, and hair loss. Keep all appointments to have your blood checked. Contact your health care provider right away if you have new or worsening diarrhea, black or bloody poop, lightheadedness, dizziness, faintness, trouble drinking enough fluid due to nausea or vomiting, or trouble getting diarrhea under control within 24 hours. Also tell your health care provider right away if you get a fever or infection.

Uses

What is irinotecan used for?

Irinotecan is commonly used to treat certain people with cancer in the colon or rectum (colorDectal cancer).

Irinotecan may also be used for other conditions as determined by your health care provider.

How does irinotecan work (mechanism of action)?

Irinotecan kills cancer cells by causing damage to their DNA.

How is irinotecan supplied (dosage forms)?

Irinotecan is available in an injectable form that is given by a healthcare provider.

How should I store irinotecan?

Irinotecan is usually given by a health care provider in a hospital or clinic. You will not store it at home.

Side Effects

What are the most common side effects of irinotecan?

The most common side effects of irinotecan are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Nausea and vomiting
  • Stomach pain
  • Diarrhea (see below)
  • Constipation
  • Loss of appetite
  • Mouth or lip sores
  • Bone marrow suppression (see below)
  • Feeling unusually weak or tired
  • Pain
  • Fever
  • Infection
  • Changes in bilirubin levels
  • Hair loss
  • Weight loss

There may be other side effects of irinotecan that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of irinotecan?

While less common, the most serious side effects of irinotecan are described below, along with what to do if they happen.

Severe Allergic Reactions. Irinotecan may cause allergic reactions, which can be serious. Stop using irinotecan and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Diarrhea. Diarrhea is common with irinotecan. It may occur during your irinotecan infusion or shortly after (early diarrhea), or it can happen more than 24 hours after you receive irinotecan (late diarrhea). Early diarrhea usually does not last long, but late diarrhea can be serious, even life-threatening. It is important to tell your health care provider right away if you have late diarrhea. If you are given medicine to prevent or treat diarrhea, take it exactly as your health care provider tells you. Keep track of how many bowel movements (poops) you have each day so that you can let your health care provider know. Call your health care provider right away if you have any of the following.

  • Diarrhea for the first time during treatment
  • Black or bloody stool (poop)
  • Lightheadedness, dizziness, or faintness
  • Trouble drinking water due to nausea or vomiting
  • Trouble getting diarrhea under control within 24 hours

Bone Marrow Suppression. Irinotecan may cause your bone marrow to not make enough cells. This can lead to low blood levels of important cells, such as red blood cells, white blood cells, platelets, and neutrophils. Bone marrow suppression can lead to infections or bleeding. This can be serious or even life-threatening. Keep all appointments to have your blood checked. Tell your health care provider right away if you have any of the following symptoms of bone marrow suppression.

  • Fever
  • Shortness of breath
  • Pale or yellowish skin
  • Easy bruising or bleeding
  • Frequent infection
  • Unusual weakness or tiredness
  • Dizziness, lightheadedness, or feeling like you are about to pass out
  • Headache
  • Fast or abnormal heartbeat

Kidney Damage. Kidney damage can happen when receiving irinotecan, especially in people who become dehydrated due to severe vomiting or diarrhea. Try to drink water or use electrolyte replacement products to help prevent dehydration. Call your health care provider right away if you have any of the following symptoms of kidney damage or if you are unable to stay hydrated.

  • Reduced need to pee
  • Swelling in your feet, ankles, or legs
  • Weakness or unusual tiredness
  • A hard time catching your breath or chest pain/pressure
  • Confusion
  • Nausea
  • Seizures

Lung Problems. Lung problems can happen when receiving irinotecan, which can be serious or even life-threatening. Contact your health care provider right away if you have any of the following new or worsening symptoms of lung problems.

  • Shortness of breath
  • Cough
  • Fever

Tissue Irritation. Irinotecan is given as an infusion into a vein. If the medicine does not go into your vein, it could irritate nearby tissue. Tell your health care provider right away if you have pain, swelling, warmth, or skin color changes where the medicine is being or was given.

Warnings & Precautions

Who should not use irinotecan?

Allergies to Ingredients. People who are allergic to any of the following should not use irinotecan.

  • Camptosar
  • Irinotecan
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific irinotecan products they stock.

What should I know about irinotecan before using it?

Irinotecan is usually given by a health care provider in a hospital or clinic. 

Irinotecan can affect your vision and make you feel dizzy, especially within 24 hours of receiving a dose. Do not drive or do other activities that require good vision or coordination within 24 hours of receiving irinotecan until you know how the medicine affects you.

People who are older than 65 can be at greater risk of some side effects from irinotecan. Talk to your health care provider about your risks if you are in this age group.

Irinotecan may make it hard for you to get pregnant or get your partner pregnant. If you may want children one day, talk to your health care provider.

Your health care provider may conduct a test for a genetic variation in an enzyme called UGT1A1, which the body needs to break down irinotecan, before you start treatment. This is to make sure you are not at an increased risk of side effects with normal doses of irinotecan.

If you can get pregnant, use effective birth control while using irinotecan and for six months after your last dose. If you can get your partner pregnant, use effective birth control like condoms with spermicide while using irinotecan and for three months after your last dose. Talk to your health care provider about your birth control options. 

What should I tell my health care provider before using irinotecan?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if irinotecan is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Prior or future radiation therapy
  • Liver or gallbladder problems, including Gilbert’s syndrome
  • Lung problems
  • Kidney problems, including dialysis use

Vaccines. Talk to your health care provider about any vaccines that you may need. You should not receive certain vaccines right before or while using irinotecan. Tell your health care provider about any vaccines you have recently received or have scheduled.

Other Medicines and Supplements. Irinotecan may interact with other medicines and supplements. Before using irinotecan, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. Irinotecan can harm a fetus. Your health care provider will likely do a test to make sure you are not pregnant before starting irinotecan. Tell your health care provider right away if you are pregnant, think you may be pregnant, or plan to become pregnant.

Breastfeeding. Irinotecan passes into breast milk. Do not breastfeed during treatment with irinotecan and for seven days after your last dose. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does irinotecan interact with foods or drinks?

There are no known interactions between irinotecan and foods or drinks.

There are no known interactions between irinotecan and alcohol, but heavy drinking can slow your immune response and make it harder for your body to fight cancer.

Does irinotecan interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before using irinotecan.

  • Carbamazepine (Carbatrol, Tegretol, and others), which is a medicine commonly used to treat seizures or nerve pain
  • Phenobarbital or phenytoin (Dilantin, Phenytek, and others), which is a medicine to control seizures
  • St. John’s wort, which is a supplement that may be used for depression
  • Rifampin (Rifadin), which is a medicine commonly used to treat an infection called tuberculosis
  • Rifabutin (Mycobutin), which is a medicine used to prevent Mycobacterium avium complex infection
  • Itraconazole (Sporanox, Tolsura), ketoconazole, or voriconazole (Vfend), which are medicines used for fungal infections
  • Clarithromycin, which is an antibiotic used to treat various infections
  • A protease inhibitor, such as atazanavir (Reyataz), nelfinavir (Viracept), or ritonavir (Norvir), which is a medicine commonly used to treat HIV
  • Lopinavir/ritonavir (Kaletra), which is a medicine used to treat HIV
  • Nefazodone, which is a medicine used to treat depression
  • Gemfibrozil (Lopid), which is a medicine used to lower triglycerides

Many other medicines may alter the blood levels of irinotecan. Tell your health care provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with irinotecan. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much irinotecan?

If you or someone else has used too much irinotecan, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of irinotecan?

Irinotecan is usually given by a health care provider in a hospital. Your health care provider will make sure you are receiving irinotecan as scheduled.

If you miss an appointment to get your irinotecan dose, call to make another appointment as soon as possible.