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Premarin Side Effects

Generic name: conjugated estrogens

Medically reviewed by Drugs.com. Last updated on Dec 24, 2023.

Note: This document contains side effect information about conjugated estrogens. Some dosage forms listed on this page may not apply to the brand name Premarin.

Applies to conjugated estrogens: oral tablet. Other dosage forms:

Warning

Oral route (Tablet)

Endometrial Cancer, Cardiovascular Disorders, Breast Cancer and Probable DementiaEstrogen-Alone TherapyThere is an increased risk of endometrial cancer in a woman with a uterus who uses unopposed estrogens.Estrogen-alone therapy should not be used for the prevention of cardiovascular disease or dementia.Women's Health Initiative estrogen-alone substudy reported increased risks of stroke and deep vein thrombosis.The Women’s Health Initiative Memory Study estrogen-alone ancillary study of Women’s Health Initiative reported an increased risk of probable dementia in postmenopausal women 65 years of age and older.Estrogen Plus Progestin TherapyEstrogen plus progestin therapy should not be used for the prevention of cardiovascular disease or dementia.The Women’s Health Initiative estrogen plus progestin substudy reported increased risks of stroke, DVT, pulmonary embolism, and myocardial infarction.The Women’s Health Initiative estrogen plus progestin substudy reported increased risks of invasive breast cancer.The Women’s Health Initiative Memory Study estrogen plus progestin ancillary study of Women’s Health Initiative reported an increased risk of probable dementia in postmenopausal women 65 years of age and older.

Serious side effects of Premarin

Along with its needed effects, conjugated estrogens (the active ingredient contained in Premarin) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking conjugated estrogens:

More common

Less common

Incidence not known

Other side effects of Premarin

Some side effects of conjugated estrogens may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

Incidence not known

For Healthcare Professionals

Applies to conjugated estrogens: injectable powder for injection, oral tablet, vaginal cream.

Cardiovascular

Common (1% to 10%): Hypertension, palpitation, vasodilation

Rare (less than 0.1%): Stroke

Postmarketing reports: Deep and superficial venous thrombosis, pulmonary embolism, thrombophlebitis, myocardial infarction, stroke[Ref]

-HRT is associated with a 1.3 to 3-fold increased relative risk of developing VTE, i.e., deep vein thrombosis or pulmonary embolism. This event is more likely to occur in the first year of using HRT.

-The use of estrogen-only and estrogen-progestin therapy is associated with an up to 1.5 fold increased relative risk of ischemic stroke.

-The risk of hemorrhagic stroke is not increased during use of HRT. This relative risk is not dependent on age or on duration of use, but as the baseline risk is strongly age-dependent, the overall risk of stroke in women who use HRT will increase with age.[Ref]

Dermatologic

Common (1% to 10%): Acne, alopecia, hirsutism, pruritus, rash, skin discoloration, sweating, fungal dermatitis

Postmarketing reports: Chloasma or melasma (may persist when drug is discontinued), erythema multiforme, erythema nodosum, loss of scalp hair[Ref]

Gastrointestinal

Common (1% to 10%): Constipation, diarrhea, dyspepsia, eructation, flatulence, nausea

Uncommon (0.1% to 1%): Bloating, abdominal pain

Postmarketing reports: Vomiting, abdominal discomfort, abdominal distension[Ref]

Genitourinary

Common (1% to 10%): Pelvic pain, breast disorder, breast enlargement, breast neoplasm, breast pain, cervix disorder, dysmenorrhea, endometrial disorder, endometrial hyperplasia, leukorrhea, metrorrhagia, urinary tract infection, uterine fibroids enlarged, uterine spasm, abnormal uterine bleeding (breakthrough bleeding/spotting), vaginal dryness, vaginal hemorrhage, vaginal moniliasis, vaginitis

Uncommon (0.1% to 1%): Vaginal candidiasis, changes in menstrual flow, changes in cervical ectropion and secretion

Postmarketing reports: Increases in seize of uterine leiomyomata, change in cervical secretion, ovarian cancer, endometrial cancer, breast tenderness, breast discharge, galactorrhea, fibrocystic breast changes, breast cancer, gynecomastia in males[Ref]

Metabolic

Common (1% to 10%): Hyperlipidemia, weight gain, increased appetite

Very rare (less than 0.01%): Hypocalcemia

Postmarketing reports: Increase or decrease in weight, glucose intolerance, aggravation of porphyria, increased triglycerides[Ref]

Musculoskeletal

Common (1% to 10%): Back pain, arthralgia, leg cramps, myalgia, muscle spasm[Ref]

Nervous system

Common (1% to 10%): Headache, dizziness, paresthesia, migraine, hypertonia, insomnia, nervousness

Very rare (less than 0.01%): Exacerbation of chorea

Postmarketing reports: Exacerbation of epilepsy, dementia[Ref]

Other

Common (1% to 10%): Accidental injury, asthenia, chills, flu syndrome, pain, edema, peripheral edema, generalized edema, moniliasis

Postmarketing reports: Irritability[Ref]

Psychiatric

Common (1% to 10%): Depression, emotional liabilities, anxiety

Uncommon (0.1% to 1%): Changes in libido, mood disturbances[Ref]

Respiratory

Common (1% to 10%): Chest pain, bronchitis, increased cough, pharyngitis, rhinitis, sinusitis, upper respiratory tract infection

Postmarketing reports: Exacerbation of asthma[Ref]

Hepatic

Uncommon (0.1% to 1%): Gallbladder disease

Postmarketing reports: Cholestatic jaundice, pancreatitis, enlargement of hepatic hemangiomas, ischemic colitis[Ref]

Hypersensitivity

Uncommon (0.1% to 1%): Hypersensitivity

Rare (less than 0.1%): Anaphylactic/anaphylactoid reactions including urticaria and angioedema[Ref]

Ocular

Uncommon (0.1% to 1%): Intolerance to contact lenses, steepening of corneal curvature

Postmarketing reports: Retinal vascular thrombosis[Ref]

Oncologic

Breast cancer:

-An up to 2-fold increased risk of having breast cancer diagnosed is reported in women taking combined estrogen-progestin therapy for more than 5 years.

-Any increased risk in users of estrogen-only therapy is substantially lower than that seen in users of estrogen-progestin combinations. The level of risk is dependent on the duration of use.

Endometrial Cancer:

-Endometrial cancer risk is about 5 in every 1000 women with a uterus not using HRT.

-In women with a uterus, use of estrogen-only HRT is not recommended because it increases the risk of endometrial cancer.

-Depending on the duration of estrogen-only use and estrogen dose, the increase in risk of endometrial cancer varied from between 5 and 55 extra cases diagnosed in every 1000 women between the ages of 50 and 65.

-Adding a progestin to estrogen-only therapy for at least 12 days per cycle can prevent this increased risk. In the Million Women Study the use of five years of combined HRT did not increase risk of endometrial cancer.

Ovarian cancer:

-Long-term use of estrogen-only and combined estrogen-progestin HRT has been associated with a slightly increased risk of ovarian cancer. In the Million Women Study 5 years of HRT resulted in 1 extra case per 2500 users.[Ref]

Rare (0.01% to 0.1%): Breast cancer, ovarian cancer, fibrocystic breast changes, growth potentiation of benign meningioma.

Very rare (less than 0.01%): Endometrial cancer, enlargement of hepatic hemangiomas[Ref]

References

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.