aprepitant
Brand names: Emend
Aprepitant (Emend) is a medicine that helps prevent nausea and vomiting. It belongs to a class of drugs called NK1 receptor antagonists.
Drug Pricing (NADAC)
Brand Price
$325.22/unit
Generic Price
$182.16/unit
Generic Savings
44%
Generic Available
Yes (3 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Aprepitant is used to prevent nausea and vomiting caused by chemotherapy.
Common side effects
Tiredness, Diarrhea, Weakness
Key warnings
Aprepitant can interact with other medicines.
How It Works
Aprepitant blocks a substance in your body called substance P. Substance P can trigger nausea and vomiting. By blocking it, aprepitant helps reduce these side effects.
How to Take It
For chemotherapy, you will take aprepitant capsules 1 hour before your treatment on days 1, 2, and 3. The dose on day 1 is 125 mg, and on days 2 and 3 it is 80 mg. If you don't have chemotherapy on days 2 and 3, take aprepitant in the morning. For post-surgery nausea, adults take a 40 mg dose within 3 hours before anesthesia.
Pregnancy & Breastfeeding
There is not enough information about the safety of aprepitant during pregnancy. Talk to your doctor if you are pregnant or plan to become pregnant. It is not known if aprepitant passes into breast milk, so discuss breastfeeding with your doctor.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
Storage
Store aprepitant capsules at room temperature, between 68°F and 77°F.
Side Effects (from patient reports)
Based on 14,987 FDA adverse event reports.
FDA Adverse Event Report Analysis
Detailed analysis of 17,740 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
17,740
Death-Related Reports
2,942
Hospitalization Reports
9,758
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | NAUSEA | 2,145 |
| 2 | FATIGUE | 1,769 |
| 3 | PYREXIA | 1,589 |
| 4 | DIARRHOEA | 1,542 |
| 5 | DYSPNOEA | 1,508 |
| 6 | VOMITING | 1,474 |
| 7 | OFF LABEL USE | 1,340 |
| 8 | ALOPECIA | 1,274 |
| 9 | RASH | 1,210 |
| 10 | HYPERSENSITIVITY | 1,133 |
| 11 | FEBRILE NEUTROPENIA | 1,043 |
| 12 | DECREASED APPETITE | 1,038 |
| 13 | PRURITUS | 1,020 |
| 14 | STOMATITIS | 992 |
| 15 | INFUSION RELATED REACTION | 972 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Aprepitant can interact with other medicines. It can affect how well warfarin (a blood thinner) and hormonal birth control work. If you take warfarin, your doctor will check your blood. If you use hormonal birth control, use a backup method while taking aprepitant and for 28 days after your last dose.
Known Drug Interactions
Table 10: Effects of Aprepitant on the Pharmacokinetics of Other Drugs CYP3A4 Substrates Pimozide Clinical Impact Increased pimozide exposure Intervention Aprepitant is contraindicated [see Contraindications ( 4 )] . Table 10: Effects of Aprepitant on the Pharmacokinetics of Other Drugs CYP3A4 Substrates Pimozide Clinical Impact Increased pimozide exposure Intervention Aprepitant is contraindicated [see Contraindications ( 4 )] .
Mechanism: Aprepitant stops the body from breaking down pimozide, which can cause pimozide to build up to dangerous levels in the blood.
What to do: Do not take these two medications together because the combination is unsafe.
Benzodiazepines Clinical Impact Increased exposure to midazolam or other benzodiazepines metabolized via CYP3A4 (alprazolam, triazolam) may increase the risk of adverse reactions [see Clinical Pharmacology ( 12.3 )]. Benzodiazepines Clinical Impact Increased exposure to midazolam or other benzodiazepines metabolized via CYP3A4 (alprazolam, triazolam) may increase the risk of adverse reactions [see Clinical Pharmacology ( 12.3 )].
Mechanism: Aprepitant slows down how fast your body processes alprazolam, which causes the drug to build up in your blood. This can make you feel much more sleepy or dizzy than usual.
What to do: Your doctor may need to lower your dose of alprazolam. Watch closely for increased side effects like extreme drowsiness.
Intervention Avoid concomitant use of aprepitant Examples Moderate inhibitor: diltiazem Strong inhibitors: ketoconazole, itraconazole, nefazodone, troleandomycin, clarithromycin, ritonavir, nelfinavir Strong CYP3A4 Inducers Clinical Impact Substantially decreased exposure of aprepitant in patients chronically taking a strong CYP3A4 inducer may decrease the efficacy of aprepitant [see Clinical Pharmacology ( 12.3 )] . Intervention Avoid concomitant use of aprepitant Examples Moderate inhibitor: diltiazem Strong inhibitors: ketoconazole, itraconazole, nefazodone, troleandomycin, clarithromyci...
Mechanism: Diltiazem slows down the body's ability to process aprepitant, which can increase the amount of aprepitant in your blood.
What to do: Avoid taking these two medications at the same time.
Single 40 mg dose of aprepitant No dosage adjustment of oral dexamethasone needed Methylprednisolone Clinical Impact Increased methylprednisolone exposure [see Clinical Pharmacology ( 12.3 )]. Intervention 3-day aprepitant regimen Reduce the dose of intravenous methylprednisolone by approximately 25% Reduce the dose of oral methylprednisolone by approximately 50% Single 40 mg dose of aprepitant No dosage adjustment of methylprednisolone needed Chemotherapeutic agents that are metabolized by CYP3A4 Clinical Impact Increased exposure of the chemotherapeutic agent may increase the risk of adve...
Mechanism: Aprepitant prevents the body from breaking down methylprednisolone, which leads to higher levels of the steroid in your system.
What to do: Your doctor should reduce your dose of methylprednisolone by 25% to 50% depending on how it is given.
Intervention Avoid concomitant use of aprepitant Examples Moderate inhibitor: diltiazem Strong inhibitors: ketoconazole, itraconazole, nefazodone, troleandomycin, clarithromycin, ritonavir, nelfinavir Strong CYP3A4 Inducers Clinical Impact Substantially decreased exposure of aprepitant in patients chronically taking a strong CYP3A4 inducer may decrease the efficacy of aprepitant [see Clinical Pharmacology ( 12.3 )] . Intervention Avoid concomitant use of aprepitant Examples Moderate inhibitor: diltiazem Strong inhibitors: ketoconazole, itraconazole, nefazodone, troleandomycin, clarithromyci...
Mechanism: Ketoconazole strongly blocks the enzymes that clear aprepitant from your body, causing drug levels to rise.
What to do: You should avoid using these two medications together.
Common Questions
Can I take aprepitant with food?
What should I do if I experience side effects?
Can I take aprepitant if I am allergic to any of its ingredients?
Can aprepitant be used to treat nausea that has already started?
How long can I take aprepitant?
What dose of aprepitant should I take for chemotherapy?
What dose of aprepitant should I take for post-operative nausea?
Can children take aprepitant?
What if I am taking other medications?
Are there any reasons I should not take aprepitant?
What are the common side effects of aprepitant?
Does aprepitant interact with other medications?
What drug class is aprepitant?
Is there a generic version of aprepitant?
Is aprepitant safe during pregnancy?
Has aprepitant been recalled?
Active Recalls
Presence of particulate matter: potential presence of metal particulates in the product.
Merck Sharp & Dohme LLC
Related Medications in NK1 Receptor Antagonist (Antiemetic)
Other drugs grouped near aprepitant — same-class peers and common alternatives.
alosetron
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bisacodyl
Dulcolax
Bisacodyl is a medicine that helps you have a bowel movement.
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bismuth subsalicylate
Pepto-Bismol
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cimetidine
Tagamet
Cimetidine (Tagamet) reduces stomach acid.
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dexlansoprazole
Dexilant
Dexlansoprazole (Dexilant) is a medicine that lowers stomach acid.
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Medication Guides
Understanding Drug Interactions
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FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
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Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for aprepitant
The FDA label for aprepitant (sold under brand names such as Emend) classifies it as a prescription-only medication in the NK1 Receptor Antagonist (Antiemetic) class. Aprepitant is used to prevent nausea and vomiting caused by chemotherapy. Official labeling lists 17 commonly reported side effects, including Tiredness, Diarrhea, Weakness.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 14,987 voluntary reports. The database also lists 22 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated major severity. NADAC pricing from CMS shows a generic unit cost of $182.16 versus $325.22 for the brand — a 44% generic savings.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history (currently 1 recall record on file), and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: October 16, 2025
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages