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Fosaprepitant Side Effects

For the Consumer

Applies to fosaprepitant: intravenous powder for solution

Along with its needed effects, fosaprepitant may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking fosaprepitant:

More common
  • Black, tarry stools
  • blurred vision
  • chills
  • confusion
  • cough
  • decreased urination
  • difficult or labored breathing
  • dizziness
  • dry mouth
  • fainting
  • fever
  • increase in heart rate
  • lightheadedness
  • lower back or side pain
  • nervousness
  • pain, swelling, or redness at the injection site
  • painful or difficult urination
  • pale skin
  • pounding in the ears
  • rapid breathing
  • slow or fast heartbeat
  • sore throat
  • sunken eyes
  • tenderness, swelling, warmth, or skin discoloration at the injection site
  • thirst
  • tightness in the chest
  • ulcers, sores, or white spots in the mouth
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • wrinkled skin
Less common
  • Hard lump at the injection site
  • Blood in the urine
  • changes in patterns and rhythms of speech
  • changes in skin color
  • chest pain or discomfort
  • fast, slow, irregular, pounding, or racing heartbeat or pulse
  • general feeling of discomfort or illness
  • headache
  • increased sweating
  • increased thirst
  • lightheadedness, dizziness, or fainting
  • loss of consciousness
  • muscle pain or cramps
  • nausea
  • pain, tenderness, or swelling of the foot or leg
  • seizures
  • slurred speech
  • swelling
  • swelling of the face, ankles, or hands
  • trouble with speaking
  • troubled breathing with exertion
  • vomiting
Incidence not known
  • Diarrhea
  • difficulty with swallowing
  • hives or welts, itching
  • joint pain
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or genitals
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • redness of the skin

Some side effects of fosaprepitant may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Belching
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • continuing ringing or buzzing or other unexplained noise in ears
  • difficulty having a bowel movement
  • dizziness
  • feeling of indigestion
  • hair loss or thinning of the hair
  • hearing loss
  • hiccups
  • indigestion
  • lack or loss of strength
  • loss of appetite
  • pain in the chest below the breastbone
  • stomach discomfort, upset, or pain
  • swelling or inflammation of the mouth
  • weight loss
Less common
  • Feeling of warmth
  • pain or discomfort in chest, upper stomach, or throat
  • redness of the face, neck, arms, and occasionally, upper chest
  • sudden sweating
  • unusually warm skin
  • Abnormal dreams
  • blemishes on the skin
  • bumps on the skin
  • burning, dry, or itching eyes
  • change in taste
  • change in walking and balance
  • clumsiness or unsteadiness
  • confusion about identity, place, and time
  • difficulty with moving
  • discharge, excessive tearing
  • excess air or gas in the stomach
  • extreme thirst
  • false or unusual sense of well-being
  • flushed, dry skin
  • frequent urination
  • fruit-like breath odor
  • full feeling
  • heartburn
  • increased hunger
  • increased sensitivity of the skin to sunlight
  • increased urination
  • increased volume of pale, dilute urine
  • muscle ache, cramp, stiffness, or weakness
  • oily skin
  • passing gas
  • pimples
  • redness or other discoloration of the skin
  • redness, pain, or swelling of the eye, eyelid, or inner lining of the eyelid
  • severe constipation
  • severe sunburn
  • sleepiness
  • stomach distension
  • sweating
  • swollen joints
  • trouble performing routine tasks
  • trouble sleeping
  • unexplained weight loss
  • unusual drowsiness, dullness, or feeling of sluggishness
  • weight gain
  • white patches with diaper rash

For Healthcare Professionals

Applies to fosaprepitant: intravenous powder for injection


The most common side effects include fatigue and diarrhea.[Ref]


Very common (10% or more): Fatigue (up to 15%)
Common (1% to 10%): Asthenia, pyrexia
Uncommon (0.1% to 1%): Malaise
Rare (0.01% to 0.1%): Candidiasis, staphylococcal infection, tinnitus
Frequency not reported: Postoperative infection, wound dehiscence, hypothermia, pain[Ref]


Very common (10% or more): Diarrhea (up to 13%)
Common (1% to 10%): Dyspepsia, constipation
Uncommon (0.1% to 1%): Abdominal pain, gastroesophageal reflux disease, nausea, eructation, vomiting, dry mouth, flatulence
Rare (0.01% to 0.1%): Duodenal ulcer perforation, stomatitis, hard feces, neutropenic colitis, abdominal distension
Frequency not reported: Abdominal pain upper, bowel sounds abnormal, stomach discomfort, subileus[Ref]

Constipation and subileus occurred at higher doses.[Ref]


Common (1% to 10%): Neutropenia, anemia, leukopenia
Uncommon (0.1% to 1%): Febrile neutropenia
Rare (0.01% to 0.1%): Neutrophil count decreased
Frequency not reported: hemoglobin decreased, blood albumin decreased[Ref]


Common (1% to 10%): Infusion-site reactions, infusion site pain
Uncommon (0.1% to 1%): Injection site irritation, vessel puncture-site pain, infusion site thrombophlebitis, infusion site erythema, infusion site pruritus, infusion site induration[Ref]

Infusion site reactions occurred in 2.2% of patients, compared to 0.6% given ondansetron and dexamethasone (standard therapy). These reactions included infusion site pain, injection site irritation, vessel-puncture site pain, and infusion site thrombophlebitis.[Ref]


Common (1% to 10%): ALT increased, AST increased
Frequency not reported: Blood bilirubin increased[Ref]

Nervous system

Common (1% to 10%): Peripheral neuropathy, headache
Uncommon (0.1% to 1%): Dizziness, somnolence
Rare (0.01% to 0.1%): Cognitive disorder, lethargy, gait disturbance, dysgeusia
Frequency not reported: Hypoesthesia, syncope, sensory disturbance, dysarthria
Postmarketing reports: Ifosfamide-induced neurotoxicity[Ref]

Ifosfamide-induced neurotoxicity occurred after coadministration with ifosfamide.[Ref]


Common (1% to 10%): Bradycardia
Uncommon (0.1% to 1%): Blood pressure increased/hypertension, blood pressure decreased/hypotension, thrombophlebitis, palpitations, hot flush
Rare (0.01% to 0.1%): Cardiovascular disorder, chest discomfort, edema
Frequency not reported: Operative hemorrhage, hematoma[Ref]


Common (1% to 10%): Decreased appetite
Uncommon (0.1% to 1%): Blood alkaline phosphatase increased
Rare (0.01% to 0.1%): Polydipsia, blood sodium decreased, weight decrease
Frequency not reported: blood glucose increased, blood potassium decreased/hypokalemia, hypovolemia[Ref]


Common (1% to 10%): Hiccups
Rare (0.01% to 0.1%): Cough, oropharyngeal pain, postnasal drip, sneezing, throat irritation
Frequency not reported: Dyspnea, respiratory depression, hypoxia, wheezing[Ref]


Common (1% to 10%): Insomnia
Uncommon (0.1% to 1%): Anxiety
Rare (0.01% to 0.1%): Disorientation, euphoric mood[Ref]


Common (1% to 10%): Urinary tract infection
Uncommon (0.1% to 1%): Dysuria
Rare (0.01% to 0.1%): Pollakiuria, red blood cells urine positive, glucose urine present, urine output increased[Ref]


Common (1% to 10%): Pain in extremity
Rare (0.01% to 0.1%) Muscular weakness, muscle spasms[Ref]


Uncommon (0.1% to 1%): Erythema, flushing, acne, rash
Rare (0.01% to 0.1%): Hyperhidrosis, seborrhea, photosensitivity reaction, rash pruritic, skin lesion, Stevens-Johnson syndrome, toxic epidermal necrolysis
Postmarketing reports: Pruritus, urticaria[Ref]


Rare (0.01% to 0.1%): Conjunctivitis
Frequency not reported: Visual acuity reduced, miosis[Ref]


Frequency not reported: Angioedema
Postmarketing reports: Hypersensitivity reactions, anaphylactic reactions[Ref]


1. Cerner Multum, Inc. "Australian Product Information." O 0

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. "Product Information. Emend for Injection (fosaprepitant)." Merck & Company Inc, West Point, PA.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.