Fosaprepitant is used with other medications to help prevent nausea and vomiting caused by cancer drug treatment (chemotherapy). Fosaprepitant works by blocking one of the body's natural substances (substance P/neurokinin 1) that causes vomiting.

This medication will not treat nausea or vomiting that has already started. Ask your doctor what you should do if you already have nausea or vomiting.

Read the Patient Information Leaflet if available from your pharmacist before you start using fosaprepitant and each time you get treatment. If you have any questions, ask your doctor or pharmacist.

This medication is given by injection into a vein by a health care professional as directed by your doctor. The infusion of this medication is usually finished about 30 minutes before the start of chemotherapy. Your doctor may also direct you to take a form of this medication given by mouth (aprepitant) for the next 2 days. Follow your doctor's instructions carefully. Children's dosage is based on weight and age. If you have any questions, ask your doctor or pharmacist.

Severe allergic reactions may happen during the infusion of this drug and for a short time afterward. Get medical help right away if you have any symptoms of allergic reactions such as flushing, redness, or trouble breathing. Your doctor may stop your treatment.

Tell your doctor if you vomit or feel nauseated.

See also How to Use section.

Tiredness or hiccups may occur. If either of these effects lasts or gets worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including:

• redness/sores/pain/swelling at or near the injection site

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before using fosaprepitant, tell your doctor or pharmacist if you are allergic to it; or to aprepitant; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• liver disease

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

It is unknown if this drug passes into breast milk. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Other medications can affect the removal of fosaprepitant from your body, which may affect how fosaprepitant works. Examples include azole antifungals (such as itraconazole, ketoconazole), diltiazem, macrolide antibiotics (such as clarithromycin, erythromycin), nefazodone, HIV protease inhibitors (such as nelfinavir), rifamycins (such as rifampin, rifabutin), ritonavir, St. John's wort, certain anti-seizure medicines (such as carbamazepine, phenytoin), among others.

Fosaprepitant can both speed up or slow down the removal of other medications from your body, which may affect how they work. Examples of affected drugs include flibanserin, lomitapide, pimozide, among others.

If you take warfarin, this drug may affect how well warfarin works in your body. Your doctor should test your blood during the 2 weeks after your fosaprepitant treatment to measure how well warfarin is working.

This medication may decrease the effectiveness of hormonal birth control such as pills, patch, or ring. This could cause pregnancy. Discuss with your doctor or pharmacist if you should use reliable backup birth control methods while using this medication and for 1 month after the last dose. Also tell your doctor if you have any new spotting or breakthrough bleeding, because these may be signs that your birth control is not working well.

Fosaprepitant is very similar to aprepitant. Do not use aprepitant while using fosaprepitant.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669.

Not applicable.

It is important to get each dose of this medication as scheduled. If you miss a dose, ask your doctor or pharmacist right away for a new dosing schedule. Do not double the dose to catch up.

Not applicable. This medication is given in a clinic and will not be stored at home.