Drugs › Substance P/Neurokinin-1 receptor antagonist
Generic name
Fosaprepitant: adverse event reports filed with FDA
587 reports list it as a suspect or interacting product, 2011–2026. Class: Substance P/Neurokinin-1 receptor antagonist.
- 587
- reports as suspect product
- 0% of all reports · about 39 a year
- 146
- reports, 12 months to June 2026
- 128 in the 12 months before
- 82.6%
- marked serious by the reporter
- 83.3% across the class
- 33.4%
- record death among outcomes, as reported
- 196 reports · not verified by FDA
Between July 2011 and June 2026, 587 adverse event reports received by FDA list fosaprepitant, a generic name as a suspect or interacting product. Reports that mention it only as a concomitant medication (1,110) are left out of every figure here.
In the 12 months to June 2026, 146 reports listed it, up 14% from 128 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Over its reporting history that is about 39 reports a year and 0% of the 20,646,523 reports in the database, and 6.7% of the reports for the substance P/Neurokinin-1 receptor antagonist class. How many people take it is not in the data, so a count is not a rate of occurrence.
The reactions recorded most often are dyspnoea (40%), infusion related reaction (36.1%) and hypersensitivity (33.9%). A report can list several reactions, so shares add to more than 100%; 303 different terms appear across these reports. Dyspnoea is recorded in 40% of these reports, a larger share than in the median substance P/Neurokinin-1 receptor antagonist drug (22.3%).
82.6% of the reports are marked serious by the reporter (83.3% across the class); 33.4% record death among the outcomes and 54.9% record hospitalisation, as reported. 48.4% of the reports came from other health professionals, and the largest patient age group is 18 to 44 (34.1%). FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."
Reports by month, five years
Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.
By year received
2026 covers reports received through June 2026 only.
Reactions recorded in the reports
share of Fosaprepitant reports recording the termmedian drug in substance p/neurokinin-1 receptor antagonist
- Dyspnoeashortness of breath40%235
- Infusion related reactiona reaction during or soon after an infusion36.1%212
- Hypersensitivityan allergic-type reaction33.9%199
- Glossodynia32.9%193
- Helicobacter infection32.7%192
- Confusional stateconfusion32.5%191
- Folliculitis32.2%189
- Arthralgiajoint pain32%188
- Arthropathy31.7%186
- Abdominal discomfortstomach discomfort31.5%185
- Discomfortdiscomfort31.3%184
- Fatiguetiredness31.3%184
- Gastrointestinal disorder31.3%184
- Alopeciahair loss31.2%183
- Contusiona bruise31.2%183
- Hepatic enzyme increasedraised liver enzymes31%182
- Ill-defined disordera condition that was not clearly described31%182
- Blistera blister30.8%181
- Hand deformity30.8%181
- Impaired healingslow healing30.8%181
- Pruritusitching29.1%171
- Stomatitissore mouth29.1%171
- Systemic lupus erythematosuslupus, an autoimmune disease29.1%171
- Lower respiratory tract infectiona chest infection28.8%169
- Pericarditisinflammation of the sac around the heart28.8%169
- Pemphigus28.6%168
- Muscle injury28.4%167
- Pyrexiafever28.4%167
Top 30 of 303 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 3 drugs in the substance p/neurokinin-1 receptor antagonist class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Outcomes recorded
Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 8,823 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."
Patients and reporters
Patient age
Patient sex
Who reported
Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 41.9% of reports give the United States as the country of the event or reporter.
Reason for use recorded
| Indication as recorded (MedDRA) | Reports | Share |
|---|---|---|
| Rheumatoid arthritis | 142 | 24.2% |
| Prophylaxis of nausea and vomiting | 70 | 11.9% |
| Nausea | 23 | 3.9% |
| Breast cancer | 13 | 2.2% |
| Chemotherapy side effect prophylaxis | 11 | 1.9% |
| Vomiting | 9 | 1.5% |
The indication field is filled in by the reporter and is often blank; shares are of all 587 reports.
In context
| Measure | Fosaprepitant | Substance P/Neurokinin-1 receptor antagonist | All reports |
|---|---|---|---|
| Reports as suspect product | 587 | 8,823 | 20,646,523 |
| Share of that pool | — | 6.7% | 0% |
| Reports, latest 12 months | 146 | — | 1,332,454 |
| Marked serious | 82.6% | 83.3% | 57.4% |
| Death recorded among outcomes, per 1,000 reports | 334 | 219 | 91 |
| Hospitalisation recorded, per 1,000 reports | 549 | 519 | 213 |
| Consumer-filed share | 3.9% | 15.4% | 45.8% |
| Top term, share of reports | Dyspnoea 40% | median 22.3% | 2.7% |
Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Other drugs in the substance p/neurokinin-1 receptor antagonist class
| Drug | Name type | Reports | Latest 12 months | Marked serious |
|---|---|---|---|---|
| Emend | brand | 5,750 | 161 | 77.5% |
| Aprepitant | generic | 2,486 | 328 | 96.8% |
Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.
Questions about Fosaprepitant reports
How many adverse event reports has FDA received for Fosaprepitant?
587 reports list Fosaprepitant as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 146 of them arrived in the latest 12 months. Another 1,110 list it only as a concomitant medication.
What reactions are recorded in Fosaprepitant reports?
dyspnoea (40%), infusion related reaction (36.1%), hypersensitivity (33.9%), duodenal ulcer perforation (33%) and glossodynia (32.9%). These are MedDRA preferred terms coded from what the reporter described; a report can list several, and a term's presence is not a finding that Fosaprepitant was responsible.
How serious are the reports?
82.6% are marked serious by the reporter. Among the outcomes recorded, 33.4% of reports include death and 54.9% include hospitalisation. FDA has not verified these outcomes and states that the reports "cannot be used to estimate the incidence" of the events.
Who files these reports?
other health professional (48.4%), pharmacist (25.4%) and physician (20.1%). Most reports reach FDA through the manufacturer, which must forward reports it receives.
Are reports for Fosaprepitant rising?
146 reports in the 12 months to June 2026, up 14% from 128 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Counts also move with how many people take a product, its time on the market and publicity.
Do these reports show that Fosaprepitant was responsible for these reactions?
No. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event." The reaction may relate to the condition being treated, to other medicines, or to something else.
Is this a list of the side effects of Fosaprepitant?
No. It is a count of what was reported to FDA. The adverse reactions observed in clinical studies are printed on the FDA-approved label, which a pharmacist or clinician can go through with you.
How do I report an adverse event?
Consumers and health professionals can report to FDA through MedWatch (Form FDA 3500 online, or 1-800-FDA-1088), or to the manufacturer, which must pass reports on. See the guide on how to report.
Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Fosaprepitant as a suspect or interacting product; reports listing it only as a concomitant medication (1,110) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.
Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.