Fosaprepitant is used together with other medications to prevent nausea and vomiting that may be caused by chemotherapy in adults and children at least 6 months old.

Fosaprepitant is given ahead of time and will not treat nausea or vomiting that you already have.

Fosaprepitant may also be used for purposes not listed in this medication guide.

You should not be treated with this medicine if you are allergic to fosaprepitant or aprepitant, or if you take another medicine called pimozide (Orap). Fosaprepitant can cause unwanted or dangerous effects when used with pimozide.

Tell your doctor if you have ever had:

• liver disease.

Tell your doctor if you are pregnant or breastfeeding.

Fosaprepitant can make hormonal birth control less effective, including birth control pills, injections, implants, skin patches, and vaginal rings. Use barrier birth control to prevent pregnancy: condom, diaphragm, cervical cap, or contraceptive sponge.

Keep using a barrier form of birth control for at least 1 month after each dose of fosaprepitant.

Use Emend For Injection (Intravenous) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have signs of an allergic reaction: hives, rash, itching, skin sores or peeling; warmth or tingly feeling; fast or weak heartbeats, severe dizziness; trouble breathing or swallowing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

• pain, redness, swelling, burning, blistering, or skin changes where the chemotherapy medicine was injected;
• a light-headed feeling, like you might pass out;
• pain or burning when you urinate; or
• low blood cell counts--fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath.

Common side effects may include:

• weakness, tired feeling;
• fever;
• low blood cell counts;
• painful urination;
• diarrhea, indigestion; or
• pain, numbness, or weakness in your arms or legs.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.