85/100 · Critical
Manufactured by Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc.
High Safety Concerns with Conjugated Estrogens, Particularly for Breast Cancer and Cardiovascular Events
100,524 FDA adverse event reports analyzed
Last updated: 2026-05-12
CONJUGATED ESTROGENS is a medication tracked in the FDA Adverse Event Reporting System (FAERS), manufactured by Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc.. Based on analysis of 100,524 FDA adverse event reports, CONJUGATED ESTROGENS has a safety score of 85 out of 100. This score indicates a relatively favorable safety profile, with fewer or less severe adverse events compared to many other tracked medications. The most commonly reported adverse reactions for CONJUGATED ESTROGENS include BREAST CANCER, BREAST CANCER FEMALE, DRUG INEFFECTIVE, NAUSEA, HEADACHE. This page provides a comprehensive breakdown of reported side effects, safety signals, patient demographics, and AI-powered safety analysis for CONJUGATED ESTROGENS.
Conjugated Estrogens has a safety concern score of 85 out of 100, placing it in the high concern category based on analysis of FDA adverse event data. The FDA has received approximately 100,524 adverse event reports for this medication, which is primarily manufactured by Wyeth Pharmaceuticals Llc, A Subsidiary Of Pfizer Inc..
The most commonly reported adverse events include Breast Cancer, Breast Cancer Female, Drug Ineffective. Of classified reports, 71.5% were designated as serious by the FDA, meaning they involved hospitalization, disability, or other significant medical outcomes. The most reported serious adverse event is breast cancer, with 41,265 reports out of 57,676 serious outcomes.
Cardiovascular events, including myocardial infarction and deep vein thrombosis, are also frequently reported. The majority of reports are from female patients, with 99.7% of the total reports.
Patients taking Conjugated Estrogens should monitor for the commonly reported side effects and contact their healthcare provider if they experience any unusual symptoms. Conjugated estrogens are contraindicated in patients with a history of breast cancer, thromboembolic disorders, and other serious conditions. Close monitoring is required for patients on these medications. This analysis is based on voluntary FDA adverse event reports and should not replace professional medical advice.
Conjugated Estrogens received a safety concern score of 85/100 (high concern). This is based on a 71.5% serious event ratio across 57,676 classified reports. The score accounts for 100,524 total adverse event reports and 100 distinct reaction types. This high score reflects a significant proportion of serious adverse events in the reporting data.
Adverse event reports by sex: Female: 55,238, Male: 187, Unknown: 101. The most frequently reported age groups are age 59 (1,114 reports), age 57 (1,109 reports), age 62 (1,082 reports). These demographics reflect reporting patterns and may not represent the full patient population.
Out of 57,676 classified reports for CONJUGATED ESTROGENS:
The FDA classifies an adverse event as “serious” if it results in death, hospitalization, disability, congenital anomaly, or requires intervention to prevent permanent damage.
Demographics reflect voluntary FDA adverse event reporting patterns and may not represent the full patient population.
Conjugated estrogens are contraindicated in patients with a history of breast cancer, thromboembolic disorders, and other serious conditions. Close monitoring is required for patients on these medications.
If you are taking Conjugated Estrogens, here are important things to know. The most commonly reported side effects include breast cancer, breast cancer female, drug ineffective, nausea, headache. While many of these may be mild and temporary, you should contact your healthcare provider if any symptoms are severe or persistent. Women taking conjugated estrogens should be aware of the increased risk of breast cancer and cardiovascular events and report any unusual symptoms to their healthcare provider. Patients should not use the medication off-label without consulting their healthcare provider. If you experience a serious adverse reaction, seek emergency medical attention immediately or call 911. You can report side effects to the FDA's MedWatch program at 1-800-FDA-1088.
The FDA continues to monitor the safety of conjugated estrogens and has issued warnings regarding the increased risk of breast cancer and cardiovascular events. Healthcare providers should weigh the benefits against the risks before prescribing.
The FDA has received approximately 100,524 adverse event reports associated with Conjugated Estrogens. These reports come from healthcare professionals, consumers, and manufacturers through the FDA Adverse Event Reporting System (FAERS). Note that the number of reports does not directly indicate the frequency of side effects, as adverse events are voluntarily reported and may be underrepresented.
The most frequently reported adverse events for Conjugated Estrogens include Breast Cancer, Breast Cancer Female, Drug Ineffective, Nausea, Headache. By volume, the top reported reactions are: Breast Cancer (9,620 reports), Breast Cancer Female (8,864 reports), Drug Ineffective (3,279 reports). These figures reflect FDA adverse event reports and may not represent the true incidence rate of these side effects in all patients taking Conjugated Estrogens.
Out of 57,676 classified reports, 41,265 (71.5%) were classified as serious and 16,411 as non-serious. The FDA classifies an event as "serious" if it results in death, hospitalization, disability, or other medically significant outcomes. A higher serious-event ratio warrants closer attention but does not necessarily mean the drug is unsafe.
Adverse event reports for Conjugated Estrogens break down by patient sex as follows: Female: 55,238, Male: 187, Unknown: 101. This distribution reflects reporting patterns rather than actual risk differences between groups. Reporting rates can be influenced by prescribing patterns, disease demographics, and reporting behavior.
The most frequently reported age groups for Conjugated Estrogens adverse events are: age 59: 1,114 reports, age 57: 1,109 reports, age 62: 1,082 reports, age 61: 1,044 reports, age 58: 1,032 reports. Age-related reporting patterns can reflect both the demographics of the patient population and potential age-related susceptibility to certain side effects.
The primary manufacturer associated with Conjugated Estrogens adverse event reports is Wyeth Pharmaceuticals Llc, A Subsidiary Of Pfizer Inc.. Multiple manufacturers may produce generic versions of this drug. The manufacturer listed reflects the most frequently reported brand in FDA adverse event data.
Beyond the most common reactions, other reported adverse events for Conjugated Estrogens include: Pain, Fatigue, Off Label Use, Breast Cancer Metastatic, Dizziness. Less common side effects can still be clinically significant. Patients should report any unusual symptoms to their healthcare provider.
You can report adverse events from Conjugated Estrogens to the FDA through their MedWatch program at www.fda.gov/medwatch, by calling 1-800-FDA-1088, or by completing Form FDA 3500. Healthcare professionals, consumers, and manufacturers can all submit reports. Reporting helps the FDA monitor drug safety after approval.
Conjugated Estrogens has a safety concern score of 85 out of 100 (high concern). This score is calculated from the ratio of serious to non-serious adverse events, the diversity of reported reactions, and the overall volume of reports relative to usage. The most reported serious adverse event is breast cancer, with 41,265 reports out of 57,676 serious outcomes.
Key safety signals identified in Conjugated Estrogens's adverse event data include: Breast cancer is the leading serious adverse event, with a high count of 41,265 reports.. Cardiovascular events, such as myocardial infarction and deep vein thrombosis, are also significant safety signals.. Reports of drug ineffectiveness and off-label use are common, indicating potential misuse or inefficacy issues.. These signals are derived from patterns in FDA reports and should be discussed with a healthcare provider for personalized assessment.
Conjugated estrogens are contraindicated in patients with a history of breast cancer, thromboembolic disorders, and other serious conditions. Close monitoring is required for patients on these medications. Always inform your healthcare provider about all medications, supplements, and over-the-counter drugs you are taking before starting Conjugated Estrogens.
Women taking conjugated estrogens should be aware of the increased risk of breast cancer and cardiovascular events and report any unusual symptoms to their healthcare provider. Patients should not use the medication off-label without consulting their healthcare provider.
Conjugated Estrogens has 100,524 adverse event reports on file with the FDA. Cardiovascular events, including myocardial infarction and deep vein thrombosis, are also frequently reported. The volume of reports for Conjugated Estrogens reflects both the drug's usage level and the vigilance of the reporting community.
The FDA continues to monitor the safety of conjugated estrogens and has issued warnings regarding the increased risk of breast cancer and cardiovascular events. Healthcare providers should weigh the benefits against the risks before prescribing. For the most current regulatory information, check the FDA's drug labeling database or consult your pharmacist.
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