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Fosaprepitant Side Effects

Medically reviewed by Last updated on Jun 4, 2022.

For the Consumer

Applies to fosaprepitant: intravenous powder for solution

Side effects requiring immediate medical attention

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
  • chest tightness
  • 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
  • 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
  • trouble breathing
  • 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

Side effects not requiring immediate medical attention

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

Uncommon (0.1% to 1%): Malaise

Rare (0.01% to 0.1%): Tinnitus[Ref]


Constipation and subileus occurred at higher doses.[Ref]

Very common (10% or more): Diarrhea (up to 13%)

Common (1% to 10%): Constipation, dyspepsia

Uncommon (0.1% to 1%): Abdominal distention, abdominal pain, abdominal pain upper, dry mouth, eructation, flatulence, gastroesophageal reflux disease, nausea, oral candidiasis, vomiting

Rare (0.01% to 0.1%): Duodenal ulcer perforation, hard feces, neutropenic colitis, stomatitis

Frequency not reported: Bowel sounds abnormal, stomach discomfort, subileus[Ref]


Common (1% to 10%): Anemia, leukopenia, neutropenia

Uncommon (0.1% to 1%): Febrile neutropenia

Rare (0.01% to 0.1%): Neutrophil count decreased[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%): Infusion-site pain, infusion site reactions

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

Nervous system

Common (1% to 10%): Headache, peripheral neuropathy

Uncommon (0.1% to 1%): Dizziness, somnolence

Rare (0.01% to 0.1%): Cognitive disorder, dysgeusia, gait disturbance, lethargy

Frequency not reported: Dysarthria, hypoesthesia, sensory disturbance, syncope

Postmarketing reports: Ifosfamide-induced neurotoxicity[Ref]

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


Common (1% to 10%): Hiccups

Uncommon (0.1% to 1%): Cough, oropharyngeal pain, throat irritation

Rare (0.01% to 0.1%): Postnasal drip, sneezing

Frequency not reported: Dyspnea, wheezing

Postmarketing reports: Chest tightness[Ref]


Common (1% to 10%): Urinary tract infection

Uncommon (0.1% to 1%): Dysuria

Rare (0.01% to 0.1%): Glucose urine present, pollakiuria, red blood cells urine positive, urine output increased[Ref]


Common (1% to 10%): Decreased appetite

Uncommon (0.1% to 1%): Blood alkaline phosphatase increased

Rare (0.01% to 0.1%): Blood sodium decreased, polydipsia, weight decrease[Ref]


Common (1% to 10%): ALT increased, AST increased

Frequency not reported: Blood bilirubin 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%): Blood pressure increased, flushing, hot flush, palpitations, thrombophlebitis

Rare (0.01% to 0.1%): Bradycardia, cardiovascular disorder, chest discomfort, edema

Frequency not reported: Hypotension[Ref]


Uncommon (0.1% to 1%): Acne, erythema, rash

Rare (0.01% to 0.1%): Hyperhidrosis, photosensitivity reaction, rash pruritic, seborrhea, skin lesion, Stevens-Johnson syndrome, toxic epidermal necrolysis

Frequency not reported: Pruritus, urticaria[Ref]


Uncommon (0.1% to 1%): Anxiety

Rare (0.01% to 0.1%): Disorientation, euphoric mood

Frequency not reported: Insomnia[Ref]


Rare (0.01% to 0.1%): Candidiasis, staphylococcal infection[Ref]


Rare (0.01% to 0.1%): Conjunctivitis

Frequency not reported: Miosis, visual acuity reduced[Ref]


Frequency not reported: Anaphylactic reactions, anaphylactic shock, angioedema, hypersensitivity reactions, immediate hypersensitivity reactions[Ref]

Frequently asked questions


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

2. "Product Information. Emend for Injection (fosaprepitant)." Merck & Company Inc (2008):

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

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.