Irinotecan is used alone or in combination with other medications to treat colon or rectal cancer (cancer that begins in the large intestine). Irinotecan is in a class of antineoplastic medications called topoisomerase I inhibitors. It works by stopping the growth of cancer cells.

Irinotecan injection must be given under the supervision of a doctor who is experienced in giving chemotherapy medications for cancer.

You may experience the following symptoms while you are receiving a dose of irinotecan or for up to 24 hours afterward: runny nose, increased saliva, shrinking pupils (black circles in the middle of the eyes), watery eyes, sweating, flushing, diarrhea (sometimes called 'early diarrhea'), and stomach cramps. Tell your doctor if you experience any of these symptoms. Your doctor can give you medication to prevent or treat these symptoms.

You may also experience severe diarrhea (sometimes called ''late diarrhea'') more than 24 hours after you receive irinotecan. This type of diarrhea can be life threatening since it can last a long time and lead to dehydration, infection, kidney failure, and other problems. Tell your doctor if you have or have ever had a bowel obstruction (blockage in your intestine). Tell your doctor and pharmacist if you are taking any of the following medications: other chemotherapy medications for cancer; diuretics ('water pills'); or laxatives such as bisacodyl (Dulcolax) or senna (in Correctol, Ex-Lax, Peri-Colace, Senokot).

Before you begin your treatment with irinotecan, talk to your doctor about what to do if you have late diarrhea. Your doctor will probably tell you to keep loperamide (Imodium AD) on hand so that you can begin to take it right away if you develop late diarrhea. Your doctor will probably tell you to take loperamide at regular intervals throughout the day and night. Be sure to follow your doctor's directions for taking loperamide; these will be different than the directions printed on the package label of loperamide. Your doctor will also tell you which foods you should eat and which foods you should avoid to control diarrhea during your treatment. Drink plenty of fluids and follow this diet carefully.

Call your doctor right away the first time you have diarrhea during your treatment. Also call your doctor immediately if you experience any of the following symptoms: fever (temperature higher than 100.4°F); shaking chills; black or bloody stools; diarrhea that does not stop within 24 hours; lightheadedness, dizziness, or fainting; or severe nausea and vomiting that stops you from drinking anything. Your doctor will watch you carefully and may treat you with fluids or antibiotics if needed.

Irinotecan may cause a decrease in the number of blood cells made by your bone marrow. Tell your doctor if you have or have ever had a blood disease or Gilbert's syndrome (decreased ability to break down bilirubin, a natural substance in the body) and if you are being treated with radiation to your stomach or pelvis (area between the hip bones) or if you have ever been treated with this type of radiation. If you experience any of the following symptoms, call your doctor immediately: fever, chills, cough, or other signs of infection; shortness of breath; fast heartbeat; headache; dizziness; pale skin; confusion; extreme tiredness, or unusual bleeding or bruising.

Keep all appointments with your doctor and the laboratory. Your doctor will order certain tests to check your body's response to irinotecan.

Talk to your doctor about the risks of using irinotecan.

Irinotecan comes as a liquid to be given over 90 minutes intravenously (into a vein) by a doctor or nurse. It is usually given not more often than once a week, according to a schedule that alternates one or more weeks when you receive irinotecan with one or more weeks when you do not receive the medication. Your doctor will choose the schedule that will work best for you.

Your doctor may need to delay your treatment and adjust your dose if you experience certain side effects. Be sure to tell your doctor how you are feeling during your treatment with irinotecan.

Your doctor may give you medication to prevent nausea, vomiting before you receive each dose of irinotecan. Your doctor may also give you other medication(s) to prevent or treat other side effects.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Before receiving irinotecan,

• tell your doctor and pharmacist if you are allergic to irinotecan, sorbitol, or any other medications.
• tell your doctor if you are taking ketoconazole (Nizoral). Your doctor will probably tell you not to take ketoconazole for one week before you begin your treatment with irinotecan or during your treatment.
• tell your doctor if you are taking St. John's wort. You should not take St. John's wort for 2 weeks before you begin your treatment with irinotecan or during your treatment.
• tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements and herbal products you are taking or plan to take. Be sure to mention any of the following: atazanavir (Reyataz); gemfibrozil (Lopid); medications for seizures such as carbamazepine (Carbatrol, Epitol, Tegretol), phenobarbital (Luminal), phenytoin (Dilantin, Phenytek); rifabutin (Mycobutin); and rifampin (Rifadin, Rimactane, in Rifamate and Rifater). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you have or have ever had diabetes; fructose intolerance (inability to digest the natural sugar found in fruit); or liver, lung, or kidney disease.
• tell your doctor if you are pregnant, plan to become pregnant, or plan to father a child. You or your partner should not become pregnant while you are receiving irinotecan. You will need to have a negative pregnancy test before you begin receiving this medication. If you are female, use effective birth control during your treatment and for 6 months after your final dose. If you are a male and your partner can become pregnant, you should use effective birth control (condoms) during your treatment and for 3 months after your final dose. If you or your partner become pregnant while receiving irinotecan, call your doctor. Irinotecan may harm the fetus.
• tell your doctor if you are breastfeeding. You should not breastfeed while you are receiving irinotecan injection, and for 7 days after your final dose.
• you should know that this medication may decrease fertility in men and women. Talk to your doctor about the risks of receiving irinotecan injection.
• if you are having surgery, including dental surgery, tell the doctor or dentist that you are receiving irinotecan.
• you should know that irinotecan may make you dizzy or affect your vision, especially during the first 24 hours after you receive a dose. Do not drive a car or operate machinery until you know how this medication affects you.
• talk to your doctor before you receive any vaccinations during your treatment with irinotecan.

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Symptoms of overdose may include:

• sore throat, fever, chills, cough and other signs of infection
• severe diarrhea

Your doctor will tell you about a special diet to follow to help control diarrhea during your treatment. Follow these instructions carefully.

Talk to your doctor about eating grapefruit and drinking grapefruit juice while receiving this medicine.

Irinotecan may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• nausea
• vomiting
• constipation
• swelling and sores in the mouth
• heartburn
• loss of appetite
• weight loss
• hair loss
• weakness
• sleepiness
• pain, especially back pain

Some side effects can be serious. If you experience any of these symptoms or those listed in the IMPORTANT WARNING section, call your doctor immediately:

• chest pain
• yellowing of the skin or eyes
• swollen stomach
• unexpected or unusual weight gain
• swelling of the arms, hands, feet, ankles, or lower legs
• rash
• hives
• itching
• difficulty breathing or swallowing

Some people who received irinotecan developed blood clots in their legs, lungs, brains, or hearts. There is not enough information to tell whether irinotecan caused the blood clots. Talk to your doctor about the risks of receiving irinotecan.

Irinotecan may cause other side effects. Call your doctor if you have any unusual problems while receiving this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

Irinotecan is also sometimes used along with other medications to treat small cell lung cancer. Talk to your doctor about the risks of using this medication for your condition.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.