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Fulvestrant Side Effects

The most commonly reported side effects of fulvestrant include malignant neoplasm progression, fatigue, and nausea, based on 31,885 FDA adverse event reports from 2004 to 2025.

Fulvestrant side effects

Percentages show how often each reaction appears relative to total reports for fulvestrant.

1
Malignant Neoplasm Progression12.4%3,968
2
Fatigue12.4%3,947
3
Nausea8.8%2,793
4
Death8.3%2,631
5
Diarrhoea7.6%2,420
6
Neutropenia7.5%2,402
7
White Blood Cell Count Decreased6.7%2,126
8
Neoplasm Progression6.7%2,121
9
Metastases To Bone6.3%2,009
10
Asthenia5.1%1,636
11
Metastases To Liver5.1%1,634
12
Pain5.0%1,610
13
Breast Cancer Metastatic4.7%1,513
14
Dyspnoea4.7%1,496
15
Vomiting4.6%1,462

These are voluntary reports and do not establish that fulvestrant caused these reactions.

Report severity

80.3%Serious25,597 reports
22.7%Hospitalizations7,241 reports
15.2%Fatal4,834 reports

Seriousness is determined by the reporter, not by OpenClaim.

Fulvestrant drug interactions

Other drugs that appear in adverse event reports alongside fulvestrant. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Palbociclib40.1%12,773
2
Ribociclib14.4%4,577
3
Letrozole10.2%3,240
4
Capecitabine6.2%1,966
5
Tamoxifen-citrate5.4%1,719
6
Abemaciclib5.4%1,709
7
Zoledronic-acid5.4%1,706
8
Denosumab5.3%1,705
9
Anastrozole4.9%1,577
10
Everolimus4.5%1,439
11
Paclitaxel4.4%1,412
12
Exemestane4.3%1,369
13
Alpelisib3.9%1,237
14
Trastuzumab3.3%1,061
15
Docetaxel3.0%958

Taken alongside

1
Denosumab8.1%2,574
2
Ergocalciferol5.7%1,814
3
Acetaminophen5.0%1,593
4
Levothyroxine-sodium4.8%1,518
5
Letrozole4.6%1,480
6
Zoledronic-acid4.5%1,449
7
Calcium4.2%1,335
8
Aspirin3.5%1,113
9
Ondansetron3.4%1,084
10
Palbociclib3.3%1,040
11
Exemestane3.2%1,021
12
Omeprazole2.9%918
13
Metformin2.8%887
14
Oxycodone2.8%886
15
Amlodipine2.7%849

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports fulvestrant side effects

92.6% of fulvestrant adverse event reports involve female patients and 1.0% involve male patients. The largest age group is adult at 51%. These figures reflect who reports side effects, not underlying risk.

Sex

Female92.6%
Male1.0%
Unknown6.4%

Age group

< 2<0.1%
2–11<0.1%
12–17<0.1%
18–6450.6%
65+49.3%

What is fulvestrant used for

Conditions and purposes for which patients were taking fulvestrant when the adverse event was reported.

AdenocarcinomaAdjuvant TherapyAdrenal Gland CancerAdverse EventAnaemiaAntioestrogen TherapyAromatase Inhibition TherapyAscitesAbdominal MassAcute Lymphocytic LeukaemiaAdenocarcinomaAdjuvant TherapyAdverse Drug ReactionAlbright^s DiseaseAnaemia Vitamin B12 Deficiency

Showing 15 of 347 indications

Fulvestrant brand names and reporting trend

Fulvestrant is sold under the brand name Faslodex.

Brand names

Faslodex19,943

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking fulvestrant with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.