Drugs › Estrogen receptor antagonist
Brand name · Elacestrant
Orserdu: adverse event reports filed with FDA
6,991 reports list it as a suspect or interacting product, 2023–2026. Class: Estrogen receptor antagonist.
- 6,991
- reports as suspect product
- 0% of all reports · about 2,098 a year
- 170
- reports, 12 months to June 2026
- 1,453 in the 12 months before
- 32.4%
- marked serious by the reporter
- 72.9% across the class
- 7.5%
- record death among outcomes, as reported
- 527 reports · not verified by FDA
Between March 2023 and June 2026, 6,991 adverse event reports received by FDA list the brand name Orserdu (elacestrant) as a suspect or interacting product. Reports that mention it only as a concomitant medication (29) are left out of every figure here.
In the 12 months to June 2026, 170 reports listed it, down 88% from 1,453 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 2,098 reports a year and 0% of the 20,646,523 reports in the database, and 25.3% of the reports for the estrogen receptor antagonist class. How many people take it is not in the data, so a count is not a rate of occurrence.
The MedDRA terms listed most often are nausea (20.9%), fatigue (15.6%) and disease progression (11.1%). A report can list several reactions, so shares add to more than 100%; 606 different terms appear across these reports. Nausea is recorded in 20.9% of these reports, a larger share than in the median estrogen receptor antagonist drug (9.8%).
32.4% of the reports are marked serious by the reporter (72.9% across the class); 7.5% record death among the outcomes and 12.1% record hospitalisation, as reported. 85.2% of the reports came from consumers, and the largest patient age group is 45 to 64 (36.4%). 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 Orserdu reports recording the termmedian drug in estrogen receptor antagonist
- Nauseafeeling sick20.9%1,463
- Fatiguetiredness15.6%1,092
- Disease progressionthe disease advanced11.1%776
- Vomitingbeing sick9.6%674
- Diarrhoealoose or frequent stools7.8%546
- Deaththe patient died; cause not stated by this term7.2%502
- Drug ineffectivethe medicine did not work as expected7%486
- Constipationconstipation5.7%399
- Product dose omission issuea dose was missed5.4%375
- Painpain, site not specified5.2%366
- Decreased appetitereduced appetite5.2%363
- Arthralgiajoint pain4.7%328
- Astheniaweakness or lack of energy3.5%242
- Dyspepsiaindigestion3.3%234
- Abdominal discomfortstomach discomfort3.3%233
- Tumour marker increased3.3%228
- Headachehead pain3.2%221
- Myalgiamuscle pain3%212
- Hot flusha hot flush2.7%192
- Abdominal pain upperupper stomach pain2.5%173
- Dizzinesslight-headedness or unsteadiness2.3%162
- Bone painbone pain2.3%161
- Illness2.3%161
- Malaisegeneral feeling of being unwell2.1%150
- Back painback pain2%142
- Rashskin rash1.9%136
- Pain in extremitypain in an arm or leg1.9%132
- Dyspnoeashortness of breath1.9%131
- Blood cholesterol increasedraised cholesterol1.8%129
Top 30 of 606 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 estrogen 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 27,672 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. 99% of reports give the United States as the country of the event or reporter.
Reason for use recorded
| Indication as recorded (MedDRA) | Reports | Share |
|---|---|---|
| Breast cancer female | 307 | 4.4% |
| Breast cancer metastatic | 168 | 2.4% |
| Breast cancer | 55 | 0.8% |
| Neoplasm malignant | 11 | 0.2% |
| Breast cancer male | 3 | 0% |
| Breast cancer stage iv | 3 | 0% |
The indication field is filled in by the reporter and is often blank; shares are of all 6,991 reports.
In context
| Measure | Orserdu | Estrogen receptor antagonist | All reports |
|---|---|---|---|
| Reports as suspect product | 6,991 | 27,672 | 20,646,523 |
| Share of that pool | — | 25.3% | 0% |
| Reports, latest 12 months | 170 | — | 1,332,454 |
| Marked serious | 32.4% | 72.9% | 57.4% |
| Death recorded among outcomes, per 1,000 reports | 75 | 142 | 91 |
| Hospitalisation recorded, per 1,000 reports | 121 | 207 | 213 |
| Consumer-filed share | 85.2% | 39.2% | 45.8% |
| Top term, share of reports | Nausea 20.9% | median 9.8% | 3.8% |
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 estrogen receptor antagonist class
| Drug | Name type | Reports | Latest 12 months | Marked serious |
|---|---|---|---|---|
| Fulvestrant | generic | 11,797 | 1,335 | 94.7% |
| Faslodex | brand | 8,884 | 601 | 75.9% |
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 Orserdu reports
How many adverse event reports has FDA received for Orserdu?
6,991 reports list Orserdu as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 170 of them arrived in the latest 12 months. Another 29 list it only as a concomitant medication.
What reactions are recorded in Orserdu reports?
nausea (20.9%), fatigue (15.6%), disease progression (11.1%), vomiting (9.6%) and diarrhoea (7.8%). 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 Orserdu was responsible.
How serious are the reports?
32.4% are marked serious by the reporter. Among the outcomes recorded, 7.5% of reports include death and 12.1% 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?
consumer or non-health professional (85.2%), other health professional (10.2%) and physician (3.2%). Most reports reach FDA through the manufacturer, which must forward reports it receives.
Are reports for Orserdu rising?
170 reports in the 12 months to June 2026, down 88% from 1,453 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 Orserdu 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 Orserdu?
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 Orserdu as a suspect or interacting product; reports listing it only as a concomitant medication (29) 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.