What the label lists and what reports show
Estrogens conjugated side effects
Estrogens conjugated's FDA label: “Most common adverse reactions (≥5%) are: abdominal pain, asthenia, pain, back pain, headache, flatulence, nausea, depression, insomnia, breast pain, endometrial hyperplasia, leucorrhea, vaginal hemorrhage, and vaginitis.” FAERS holds 59,243 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is breast cancer female (8,869 reports).
- Generic listed
- Boxed warning
Check it at the source: the estrogens conjugated FDA label on DailyMed (effective June 4, 2026, Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of PREMARIN?Side effects are grouped by how serious they are and how often they happen when you are treated. […]
Source: FDA drug label, Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc., effective June 4, 2026 (SPL set 258e1602-a3cf-4ccc-ca80-73dbbfb812ff), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (≥5%) are: abdominal pain, asthenia, pain, back pain, headache, flatulence, nausea, depression, insomnia, breast pain, endometrial hyperplasia, leucorrhea, vaginal hemorrhage, and vaginitis.
Table 1: Treatment-Related Adverse Reactions at a Frequency ≥1%
| Reaction | PREMARIN 0.625 mg (n=348) | PREMARIN 0.45 mg (n=338) | PREMARIN 0.3 mg (n=326) | Placebo (n=332) |
|---|---|---|---|---|
| Abdominal pain | 38 (11) | 28 (8) | 30 (9) | 21 (6) |
| Asthenia | 16 (5) | 8 (2) | 14 (4) | 3 (1) |
| Back pain | 18 (5) | 11 (3) | 13 (4) | 4 (1) |
| Chest pain | 2 (1) | 3 (1) | 4 (1) | 2 (1) |
| Generalized edema | 7 (2) | 6 (2) | 4 (1) | 8 (2) |
| Headache | 45 (13) | 47 (14) | 44 (13) | 46 (14) |
| Moniliasis | 5 (1) | 4 (1) | 4 (1) | 1 (0) |
| Pain | 17 (5) | 10 (3) | 12 (4) | 14 (4) |
| Pelvic pain | 10 (3) | 9 (3) | 8 (2) | 4 (1) |
| Hypertension | 4 (1) | 4 (1) | 7 (2) | 5 (2) |
| Migraine | 7 (2) | 1 (0) | 0 | 3 (1) |
| Palpitation | 3 (1) | 3 (1) | 3 (1) | 4 (1) |
| Vasodilatation | 2 (1) | 2 (1) | 3 (1) | 5 (2) |
| Constipation | 7 (2) | 6 (2) | 4 (1) | 3 (1) |
| Diarrhea | 4 (1) | 5 (1) | 5 (2) | 8 (2) |
| Dyspepsia | 7 (2) | 5 (1) | 6 (2) | 14 (4) |
| Eructation | 1 (0) | 1 (0) | 4 (1) | 1 (0) |
| Flatulence | 22 (6) | 18 (5) | 13 (4) | 8 (2) |
| Increased appetite | 4 (1) | 1 (0) | 1 (0) | 2 (1) |
| Nausea | 16 (5) | 10 (3) | 15 (5) | 16 (5) |
| Hyperlipidemia | 2 (1) | 4 (1) | 3 (1) | 2 (1) |
| Peripheral edema | 5 (1) | 2 (1) | 4 (1) | 3 (1) |
| Weight gain | 11 (3) | 10 (3) | 8 (2) | 14 (4) |
| Arthralgia | 6 (2) | 3 (1) | 2 (1) | 5 (2) |
| Leg cramps | 10 (3) | 5 (1) | 9 (3) | 4 (1) |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following serious adverse reactions are discussed elsewhere in labeling: • Cardiovascular Disorders [see Boxed Warning, Warnings and Precautions (5.1) ] • Malignant Neoplasms [see Boxed Warning, Warnings and Precautions (5.2) ] Most common adverse reactions (≥5%) are: abdominal pain, asthenia, pain, back pain, headache, flatulence, nausea, depression, insomnia, breast pain, endometrial hyperplasia, leucorrhea, vaginal hemorrhage, and vaginitis. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Pfizer Inc. at 1-800-438-1985 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch 6.1 Clinical Study Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. During the first year of a 2-year clinical trial with 2,333 postmenopausal women with a uterus between 40 and 65 years of age (88% Caucasian), 1,012 women were treated with CE, and 332 were treated with placebo. Table 1 summarizes treatment-related adverse reactions that occurred at a rate of ≥1% in any treatment group.
Source: FDA drug label, Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc., effective June 4, 2026 (SPL set 258e1602-a3cf-4ccc-ca80-73dbbfb812ff), via openFDA; the full label on DailyMed
What do FAERS reports show?
59,243 reports list estrogens conjugated among the medicines taken, each a report of something that happened, not proof the medicine caused it; 1,856 are coded as a death and 9,535 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 22 reactions below, 12 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Estrogens conjugated: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions