Tamoxifen adverse event reports that FDA received

Name: Reaction terms in FDA adverse event reports that name Tamoxifen
Creator: Reported Reactions
License: https://creativecommons.org/publicdomain/zero/1.0/

Name type: Product name as reported
Also reported as: Tamoxifen /00388702/

What a report is

A report is not proof that the drug was the cause of the event.

FDA says:

Adverse event reports submitted to FDA do not undergo extensive validation or verification. Therefore, a causal relationship cannot be established between product and reactions listed in a report. While a suspected relationship may exist, it is not medically validated and should not be the sole source of information for clinical decision making or other assumptions about the safety or efficacy of a product. Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product.
Source: openFDA, Drug Adverse Event Overview, section "Responsible use of the data". The site read the page on 2 Oct 2026. The data have the reports that FDA received through 30 Jun 2026.

FDA also says:

There is no certainty that the reported event (adverse event or medication error) was actually due to the product. FDA does not require that a causal relationship between a product and event be proven, and reports do not always contain enough detail to properly evaluate an event. The information in these reports has not been scientifically or otherwise verified as to a cause and effect relationship and cannot be used to estimate the incidence of these events.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

Do not rely on openFDA to make decisions regarding medical care. While we make every effort to ensure that data is accurate, you should assume all results are unvalidated.
Source: openFDA, Response of the drug event API (meta.disclaimer). The site read the page on 2 Oct 2026.

Not medical advice. This site counts what was reported to FDA. Questions about a medicine or device belong with a pharmacist or clinician.

Reports on file

From January 2004 to June 2026, FDA received 7,908 adverse event reports that name Tamoxifen. The name is as reporters wrote it. In these reports the drug is a suspect or interacting product.

In the same period, 8,484 further reports name it only as a concomitant medicine. The counts on this page do not include these reports.

FDA received 458 reports in the 12 months to June 2026 and 483 in the 12 months before. FDA releases FAERS data every quarter, so the newest months are not complete. They grow in later releases.

The number of people who use the product is not in the data. A count is not a rate. A count of reports is not a count of events or of patients, because one event can have more than one report.

There are many instances of duplicative reports and some reports do not contain all the necessary information.
Source: FDA, FDA Adverse Event Monitoring System (AEMS) Public Dashboard. Content current as of 11 Mar 2026. The site read the page on 2 Oct 2026.

Suspect product

FDA records each drug in a report as suspect, concomitant or interacting. This page counts the reports in which Tamoxifen is suspect or interacting. FDA says:

Any number of the drugs may be marked as suspect if thought to be responsible for one or more of the reactions, but that information is not validated.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

Data version

openFDA FAERS release of 1 Oct 2026. Reports received through 30 Jun 2026.

Since the last update

FDA says:

Many factors can influence whether or not an event will be reported, such as the time a product has been marketed and publicity about an event.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

The information in these reports cannot be used to estimate the incidence (occurrence rates) of the events reported.
Source: FDA, FDA Adverse Event Monitoring System (AEMS) Public Dashboard. Content current as of 11 Mar 2026. The site read the page on 2 Oct 2026.

No update is on record for this page. The record starts when FDA adds the reports of July to September 2026.

In April to June 2026, FDA received 105 reports that name Tamoxifen.
In January to March 2026, FDA received 79.
In April to June 2025, FDA received 120.

April to June 2026 is the latest closed quarter in the data. A closed quarter is a quarter for which the FDA files have most of the reports.

All updates Feed of updates (RSS)

Reaction lookup

These are the reaction terms that the reports record, with the number of reports for each term. Type a term or a plain word to find its count.

What this list leaves out

The table lists the 868 reaction terms that 5 or more reports record. A term with fewer than 5 reports is not in the table.

The site keeps reaction terms for 7,885 of the 7,908 reports (99.7%).

The reports of the other years are not in the counts.

So a count in the table can be lower than the count of FDA.

Find a reaction term

The table shows the first 50 of 868 terms.

Reaction terms in the reports that name Tamoxifen, most reports first
Reaction term (MedDRA) and plain meaning	Reports	Share of the 7,908 reports
Malignant neoplasm progression	1,274	16.1%
Metastases to bone	759	9.6%
Fatiguetiredness	601	7.6%
Breast cancer	550	7%
Metastases to liver	522	6.6%
Nauseafeeling sick	503	6.4%
Disease progressionthe disease advanced	474	6%
Drug ineffectivethe medicine did not work as expected	464	5.9%
Arthralgiajoint pain	449	5.7%
Breast cancer metastatic	409	5.2%
Diarrhoealoose or frequent stools	407	5.1%
Painpain, site not specified	370	4.7%
Deaththe patient died; cause not stated by this term	357	4.5%
Off label useused for a purpose or in a way not on the label	347	4.4%
Dyspnoeashortness of breath	331	4.2%
Headachehead pain	310	3.9%
Metastases to lung	307	3.9%
Astheniaweakness or lack of energy	297	3.8%
Neoplasm progression	283	3.6%
Vomitingbeing sick	276	3.5%
Hot flusha hot flush	269	3.4%
Malaisegeneral feeling of being unwell	255	3.2%
Neutropenialow neutrophils, a type of white blood cell	233	2.9%
Drug intolerancethe medicine was not tolerated	230	2.9%
Breast cancer recurrent	222	2.8%
Neuropathy peripheralnerve damage in hands or feet	212	2.7%
Insomniadifficulty sleeping	211	2.7%
Metastases to lymph nodes	206	2.6%
Pain in extremitypain in an arm or leg	202	2.6%
Decreased appetitereduced appetite	198	2.5%
Weight decreasedweight loss	197	2.5%
Back pain	194	2.5%
Alopeciahair loss	176	2.2%
Constipation	176	2.2%
Metastasis	175	2.2%
Dizzinesslight-headedness or unsteadiness	172	2.2%
Drug interactionan interaction between medicines	172	2.2%
Anaemialow red blood cells	165	2.1%
Rashskin rash	163	2.1%
Weight increasedweight gain	162	2%
Myalgiamuscle pain	161	2%
Bone pain	158	2%
Hypertensionhigh blood pressure	152	1.9%
Depressionlow mood	150	1.9%
Cough	149	1.9%
Pulmonary embolisma blood clot in the lung	149	1.9%
Muscle spasmsmuscle cramps	145	1.8%
Pyrexiafever	143	1.8%
Pleural effusionfluid around the lung	133	1.7%
Metastases to central nervous system	131	1.7%

Download all 868 terms of Tamoxifen (CSV)

The counts add to more than 7,908 reports, because one report can record more than one term. FDA says:

No individual drug is connected to any individual reaction. When a report lists multiple drugs and multiple reactions, there is no way to conclude from the data therein that a given drug is responsible for a given reaction.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

The CSV file has the same rows and the same limits. Its last row is a note that says so.

MedDRA term

The person who codes a report selects the preferred term that agrees best with the description of the reporter. The words under a term are the plain meaning that this site gives.

Not the label

The FDA-approved label of a product lists its adverse reactions. See the official pages at the end of this page.

Outcomes by year

The table gives the outcomes that the reporters gave, in the terms of FDA.

Outcomes in the reports that name Tamoxifen, by the year of the openFDA file that holds the report

The table continues to the right.

Year of the openFDA file	Reports	Serious	Death	Life-threatening	Hospitalization (initial or prolonged)	Disability or Permanent Damage	Congenital Anomaly/Birth Defect	Other Serious (Important Medical Events)	Not serious
2004	37	29	3	3	14	1	0	13	8
2005	37	31	1	5	14	3	0	17	6
2006	11	11	1	0	5	0	0	8	0
2007	6	5	0	1	0	1	0	4	1
2008	59	56	4	1	11	4	0	44	3
2009	14	13	2	0	3	1	1	8	1
2010	19	18	4	0	8	0	0	12	1
2011	19	18	5	0	3	2	0	11	1
2012	84	78	0	2	18	2	16	47	6
2013	366	352	17	1	52	16	0	303	14
2014	328	307	78	6	38	23	0	205	21
2015	335	278	21	11	74	16	2	220	57
2016	543	485	199	13	60	31	1	247	58
2017	420	359	25	21	74	15	1	314	61
2018	591	525	30	32	87	21	1	443	66
2019	699	665	34	24	117	25	2	578	34
2020	776	745	48	30	138	12	2	658	31
2021	918	877	46	24	181	15	4	775	41
2022	622	599	74	17	181	20	1	493	23
2023	691	670	70	27	156	16	4	587	21
2024	499	453	26	22	113	16	1	383	46
2025	599	525	27	20	148	13	3	446	74
2026	235	217	16	22	53	5	0	197	18

An outcome in a report is not proof that the drug was the cause. The reporter gives the outcome, and FDA does not verify it. FDA says:

The information in these reports has not been scientifically or otherwise verified as to a cause and effect relationship and cannot be used to estimate the incidence of these events.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

The six headings with the names of FDA are the outcome terms of FDA. A report can have more than one outcome. The columns Serious and Not serious are the two values of the openFDA field serious. For the value serious, openFDA gives this description:

The adverse event resulted in death, a life threatening condition, hospitalization, disability, congenital anomaly, or other serious condition
Source: openFDA, Drug adverse event fields (YAML reference). The site read the page on 2 Oct 2026.

The year is the year of the openFDA file that holds the latest version of the report. It is not always the year in which FDA first received the report. The chart of the next section uses the year of first receipt. The latest year is not complete.

Reports by year and month

Reports that name Tamoxifen, by the year in which FDA received them

The column of 2026 has an outline, because the year is not complete. It has the reports that FDA received through June 2026 only.

Show the figures of the chart as a table

Reports that name Tamoxifen, by the year in which FDA received them
Year	Reports
2004	25
2005	43
2006	16
2007	5
2008	61
2009	16
2010	31
2011	26
2012	105
2013	376
2014	325
2015	341
2016	553
2017	432
2018	617
2019	796
2020	879
2021	889
2022	575
2023	630
2024	457
2025	526
2026	184

Reports that name Tamoxifen, by month, five years to June 2026

FDA releases FAERS data every quarter, so the newest months are not complete. They grow in later releases.

Why a count moves

A count moves for many reasons. The guide gives FDA's words about them.

Patients and reporters

Age of the patient in the reports that name Tamoxifen
Age	Reports	Share
Under 2	14	0.2%
2 to 11	7	0.1%
12 to 17	15	0.2%
18 to 44	927	11.7%
45 to 64	2,634	33.3%
65 to 74	859	10.9%
75 and over	481	6.1%
Age not given	2,971	37.6%

Sex of the patient in the reports that name Tamoxifen
Sex	Reports	Share
Female	6,653	84.1%
Male	320	4%
Unknown or not given	935	11.8%

Type of reporter in the reports that name Tamoxifen
Reporter	Reports	Share
Physician	3,100	39.2%
Pharmacist	319	4%
Other health professional	2,248	28.4%
Lawyer	23	0.3%
Consumer or non-health professional	1,912	24.2%
Not given	306	3.9%

Age and sex are as the report gives them. The reporter is the primary source in the report. 21.8% of the reports give the United States as the country.

Reason for use

Reason for use (indication) that the reports of Tamoxifen record
Indication as recorded (MedDRA)	Reports	Share
Breast cancer	2,566	32.4%
Breast cancer metastatic	759	9.6%
Invasive ductal breast carcinoma	297	3.8%
Breast cancer female	290	3.7%
Her2 positive breast cancer	128	1.6%
Hormone receptor positive breast cancer	64	0.8%

The reporter fills in the indication, and the field is often empty. Each share is of all 7,908 reports.

Drugs in the same reports

Other drugs that the reports of Tamoxifen name, in any role, in order of name
Drug	Reports that name the two
Anastrozole	909
Capecitabine	782
Cyclophosphamide	956
Docetaxel	954
Epirubicin	570
Exemestane	733
Fulvestrant	910
Letrozole	1,627
Paclitaxel	978
Trastuzumab	784

The table has the 10 drug names that these reports name most. Two names in one report says only that the report recorded the two. It says nothing about the part of a product in the event.

FDA says:

Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

Importantly, the AEMS data by themselves are not an indicator of the safety profile of the drug or biologic.
Source: FDA, FDA Adverse Event Monitoring System (AEMS) Public Dashboard. Content current as of 11 Mar 2026. The site read the page on 2 Oct 2026.

Pages near this one

Tamiflu next in the A to Z list
Tamoxifen citrate next in the A to Z list
Tambocor next in the A to Z list
Tamsulosin next in the A to Z list
Talzenna next in the A to Z list
Tamsulosin hydrochloride next in the A to Z list
Talwin next in the A to Z list
Tamsulosin/Tamsulosin Hydrochloride next in the A to Z list
Talvey next in the A to Z list
Tamsulosina next in the A to Z list
Taltz next in the A to Z list
Tanzeum next in the A to Z list

These links are for navigation. No count selected them.

Official pages

DailyMed labels for TamoxifenThe labels (prescribing information) that have this name, at the National Library of Medicine.
MedWatch Online Voluntary Reporting FormThe online form of FDA for a voluntary report.
MedWatch: The FDA Safety Information and Adverse Event Reporting ProgramThe page of the FDA program that receives reports about drugs and devices.
FDA Adverse Event Monitoring System (AEMS) Public DashboardThe public dashboard of FDA for adverse event reports on drugs and biologics.

The site checked these addresses on 2 Oct 2026. The links open in a new tab.

Cite this page

Reported Reactions. Tamoxifen: adverse event reports that FDA received. https://reportedreactions.com/drug/tamoxifen/ Source: U.S. Food and Drug Administration, openFDA Drug Adverse Event (FAERS) files, release of 1 Oct 2026. Reports received through 30 Jun 2026.

Where the data come from

The counts come from the openFDA Drug Adverse Event (FAERS) bulk files, release of 1 Oct 2026. The files have the reports that FDA received through 30 Jun 2026. A drug name is the name on the report. The site matches it to a brand name or a generic name of the National Drug Code Directory of 2 Oct 2026. A class is the pharmacologic class (EPC) of the FDA label.

A report is in the count when it names Tamoxifen as a suspect or interacting product. The 8,484 reports that name it only as a concomitant medicine are not in the count. The site does not publish a report narrative, a lot number, a detail of a patient or the identity of a reporter. The record of FDA is the authority. See how the site counts reports, the data sources and the corrections page.

Questions

Do these reports show that Tamoxifen was responsible for the reactions?

No. FDA says:

For any given report, there is no certainty that a suspected drug caused the event.
Source: FDA, FDA Adverse Event Monitoring System (AEMS) Public Dashboard. Content current as of 11 Mar 2026. The site read the page on 2 Oct 2026.

A reaction can relate to the condition that the drug treats, to other medicines, or to something else.

Is this the list of reactions on the label of Tamoxifen?

No. It is a count of what people reported to FDA: 7,908 reports from January 2004 to June 2026. The FDA-approved label of a product lists its adverse reactions. The official pages at the end of this page link to the labels.

Who sent these reports?

Physician (39.2%), other health professional (28.4%) and consumer or non-health professional (24.2%). These are the types of reporter for the reports that name this drug.

If a manufacturer receives an adverse event report, it is normally required to send the report to FDA.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

How does a person report an adverse event?

FDA runs MedWatch, a program that takes voluntary reports from health professionals, patients and consumers. The guide on how to report has the links.

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