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Estrogens Side Effects

The most commonly reported side effects of estrogens include breast cancer, breast cancer female, and off label use, based on 70,977 FDA adverse event reports from 2004 to 2025. 4.3% of reports found the drug to be ineffective.

Estrogens side effects

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

1
Breast Cancer16.8%11,912
2
Breast Cancer Female13.3%9,474
3
Drug Ineffective4.3%3,084
4
Off Label Use3.3%2,354
5
Breast Cancer Metastatic3.0%2,119
6
Fatigue2.5%1,748
7
Headache2.5%1,744
8
Pain2.4%1,713
9
Nausea2.2%1,562
10
Malaise2.1%1,461
11
Nausea1.9%1,351
12
Hot Flush1.6%1,154
13
Arthralgia1.6%1,152
14
Cerebrovascular Accident1.6%1,137
15
Drug Ineffective1.6%1,125

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

Report severity

69.8%Serious49,548 reports
15.7%Hospitalizations11,172 reports
3.0%Fatal2,106 reports

Seriousness is determined by the reporter, not by OpenClaim.

Estrogens drug interactions

Other drugs that appear in adverse event reports alongside estrogens. 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
Medroxyprogesterone-acetate39.3%27,899
2
Estradiol6.6%4,706
3
Progesterone3.4%2,436
4
Estropipate2.7%1,919
5
Adalimumab2.3%1,660
6
Norethindrone2.1%1,494
7
Rofecoxib1.4%970
8
Etanercept1.2%878
9
Sodium-oxybate1.2%856
10
Bazedoxifene-acetate1.2%844
11
Esomeprazole1.2%836
12
Pregabalin1.1%797
13
Ethinyl-estradiol1.0%733
14
Omeprazole1.0%730
15
Varenicline0.9%673

Taken alongside

1
Levothyroxine-sodium11.2%7,915
2
Acetaminophen8.5%6,026
3
Aspirin7.2%5,083
4
Ergocalciferol6.8%4,848
5
Medroxyprogesterone-acetate5.9%4,193
6
Hydrochlorothiazide5.7%4,011
7
Omeprazole5.3%3,740
8
Gabapentin4.7%3,342
9
Albuterol4.7%3,332
10
Calcium4.7%3,304
11
Atorvastatin-calcium4.5%3,212
12
Fluticasone4.4%3,141
13
Furosemide4.3%3,052
14
Amlodipine4.1%2,899
15
Prednisone4.0%2,867

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 estrogens side effects

95.6% of estrogens adverse event reports involve female patients and 0.3% involve male patients. The largest age group is adult at 61%. These figures reflect who reports side effects, not underlying risk.

Sex

Female95.6%
Male0.3%
Unknown4.1%

Age group

< 2<0.1%
2–11<0.1%
12–170.2%
18–6461.4%
65+38.3%

What is estrogens used for

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

Abdominal DistensionAbdominal Pain LowerAcarodermatitisAcneAcromegalyActivities Of Daily Living ImpairedAddison^s DiseaseAdhesionAdnexa Uteri PainAdrenal AtrophyAdrenal InsufficiencyAdverse Drug ReactionAffect LabilityAffective DisorderAggression

Showing 15 of 912 indications

Estrogens brand names and reporting trend

Estrogens is sold under brand names including Synthetic Conjugated Estrogens A, Menest.

Brand names

Synthetic Conjugated Estrogens A8
Menest1

Quarterly reports (20042025)

20052010201520202025

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

Taking estrogens with another medication?

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