Estradiol-17β (micronized) belongs to the class of medications known as estrogen replacement therapy. Estrogen is a female hormone produced by the ovaries. Once menopause is reached, the ovaries produce less estrogen and progesterone (another hormone), and symptoms of menopause can occur.

Estradiol-17β (micronized) is an estrogen replacement hormone used to manage menopausal symptoms such as abnormal uterine bleeding, hot flashes, sweating, and chills. (See warnings about duration of use further in this article.)

It may also help to prevent osteoporosis for women when combined with diet, calcium, vitamin D, smoking cessation, and exercise. The decision to use this medication should be weighed against other options available for the treatment and prevention of osteoporosis.

Women who have not had a hysterectomy must also take a progestogen while they are taking this medication.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

Typically, estrogen is taken for the first 21 to 25 days of each month. Women who have not had a hysterectomy (i.e., they still have a uterus) should take a progestin (e.g., medroxyprogesterone) for the last 12 to 14 days of each estrogen cycle.

Women who have had a hysterectomy may take estrogen daily, without a break.

For treatment of menopausal symptoms, the usual dose is 1 mg daily for 21 to 25 days of each month. This medication should be used at the lowest effective dose for the shortest duration of time possible. Attempts to lower the dose or discontinue the medication should be made every 3 to 6 months. For prevention of osteoporosis, the usual dose is 0.5 mg daily as soon as possible after the onset of menopause. The dose may be increased or decreased according to the level of estradiol in the blood.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

0.5 mg
Each white-to-off-white, round tablet debossed with "E5" on one side and scored on the other side, contains 0.5 mg of micronized 17β-estradiol (as estradiol hemihydrate). Nonmedicinal ingredients: corn starch, colloidal silicon dioxide, copovidone, lactose monohydrate, magnesium stearate.

1 mg
Each lavender, mottled, round tablet debossed with "E1" on one side and scored on the other side, contains 1 mg of micronized 17β-estradiol (as estradiol hemihydrate). Nonmedicinal ingredients: corn starch, colloidal silicon dioxide, copovidone, lactose monohydrate, magnesium stearate, FD&C Blue No. 1, and FD&C Red No. 27.

2 mg
Each turquoise, mottled, round tablet debossed with "E2" on one side and scored on the other side, contains 2 mg of micronized 17β-estradiol (as estradiol hemihydrate). Nonmedicinal ingredients: corn starch, colloidal silicon dioxide, copovidone, lactose monohydrate, magnesium stearate, FD&C Blue No. 1, and FD&C Yellow No. 5.

Do not take estradiol-17β (micronized) if you:

• are allergic to any ingredients of the medication
• are breast-feeding
• are or may be pregnant
• have a known or suspected estrogen-dependent tumour
• have endometrial hyperplasia (thickening of the lining of the uterus)
• have had a blockage in an artery feeding the heart caused by a blood clot (coronary thrombosis)
• have had a stroke
• have had diseases of circulation or clotting
• have migraine headaches
• have had partial or complete loss of vision or double-vision from eye disease related to circulation problems
• have liver impairment or disease, especially of the obstructive type
• have or have had breast cancer or endometrial cancer, except in special circumstances
• have undiagnosed vaginal bleeding

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• acne
• bloating of stomach
• breast pain or swelling
• changes in cholesterol levels
• constipation
• dark patches on the face
• decreased interest in sexual activity
• discomfort wearing contact lenses
• dizziness
• fatigue
• hair loss
• headache (mild)
• irritability
• nausea
• stomach cramps
• vaginal itching, discharge, or pain
• vomiting
• weight changes

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• abdominal pain
• blood pressure changes
• breast lumps or discharge
• groin pain
• nervousness
• rash
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
• unexpected vaginal bleeding

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a blood clot in the eye (e.g., sudden partial or complete loss of vision)
• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• signs of a blood clot in the arm or leg (tenderness, pain, swelling, warmth, or redness in the arm or leg) or lungs (difficulty breathing, sharp chest pain that is worst when breathing in, coughing, coughing up blood, sweating, or passing out)
• signs of heart attack (e.g., sudden chest pain or pain radiating to back, down arm, jaw; sensation of fullness of the chest; nausea; vomiting; sweating; anxiety)
• signs of stroke (e.g., sudden or severe headache; sudden loss of coordination; vision changes; sudden slurring of speech; or unexplained weakness, numbness, or pain in arm or leg)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Blood clotting disorders: Estrogens should not be used if you have active thrombophlebitis or a thromboembolic disorder (diseases of blood clotting and abnormal circulation). They should also not be used (except in the treatment of cancer) if you have a history of a clotting disorder that is likely to be caused by estrogen use. Finally, they should be used under close monitoring by your doctor if you have any cerebral vascular disease or coronary artery disease, and then, only used if clearly needed.

Some studies have suggested that there is an increased relative risk for healthy women to develop deep vein thrombosis or pulmonary embolism when they use hormone replacement therapy. Women with severe varicose veins or severe obesity, and those needing to stay in bed for 3 weeks or more, are generally considered to be at increased risk of venous thromboembolism (blood clots in the bloodstream).

Blood pressure: Some women taking this medication have reported increased blood pressure. Your doctor should monitor your blood pressure if you are using estrogen, especially if high doses are used. Regular checkups by your doctor are recommended. If you have high blood pressure, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Breast cancer: Studies indicate an increased risk of breast cancer with long-term use of estrogen replacement therapy. If you have breast nodules, fibrocystic disease, abnormal mammograms, or a strong family history of breast cancer, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Women who take estrogens should have regular breast examinations and should be instructed in breast self-examination.

Cholesterol: Oral estrogens can increase triglycerides in the blood. If you have high blood cholesterol levels, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Dementia: Women over age 65 who are receiving estrogen, with or without a progestin, may be at increased risk of developing dementia (loss of memory and intellectual function). If you are over 65 years of age, your doctor should closely monitor you for loss of memory and intellectual function.

Diabetes: Estrogens can cause changes in blood glucose control for people who have diabetes or have risk factors for developing diabetes. If you have diabetes or are at risk for developing diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

People who have diabetes (or a predisposition to diabetes) should monitor their blood glucose levels closely to detect changes in blood glucose.

Endometrial cancer: There is evidence from several studies that estrogen replacement therapy increases the risk of cancer of the endometrium (uterus). Taking a progestin appropriately along with the estrogen reduces this risk to the same level as that of a woman who does not take estrogen. For this reason, all women who have not had their uterus removed should also take progestin if they use estrogens.

Fibroids: This medication may worsen fibroids, causing sudden enlargement, pain, or tenderness. If you notice these effects, contact your doctor.

Fluid retention: Estrogen may cause sodium (salt) and fluid retention. This can be dangerous for women with heart or kidney dysfunction, epilepsy, or asthma. If you have any of these conditions, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you notice the symptoms of any of these conditions getting worse, contact your doctor.

Gallbladder disease: An increased risk of gallbladder disease has been reported for postmenopausal women who take estrogens. If you have a history of gallbladder disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience symptoms of gallbladder disease, such as abdominal pain, possibly with fever and chills, contact your doctor as soon as possible.

Heart disease and stroke: Studies indicate an increased risk of heart disease and stroke with estrogen (with or without progestins) for postmenopausal women. If you experience symptoms of a heart attack (chest pain, tightness or pressure, sweating, nausea, feeling of impending doom) or stroke (sudden dizziness, headache, loss of speech, changes in vision, weakness or numbness in the arms and legs) while taking this medication, get immediate medical attention.

Liver function: If you have or have had liver problems, you may require special monitoring by your doctor while you use this medication. Make sure to tell your doctor if you have ever had liver problems.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Migraine: People who are at risk of experiencing migraine may have an increased risk of stroke when taking conjugated estrogens. If you have migraine with aura, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Ovarian cancer: Recent studies have linked long term use of estrogen with an increased risk of ovarian cancer. This increased risk appears to occur whether estrogen is used with a progestin or alone. Discuss the risks and benefits of prolonged use of hormone replacement therapy with your doctor.

Seizures: Hormone replacement therapy may increase the frequency of seizures for people with a history of seizure disorder. If you have a history of seizures, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Thyroid conditions: Estrogens can increase the amount of thyroid hormone your body needs to work properly. If you are hypothyroid (have reduced amount of thyroid hormone in your body) and need estrogens, you may require an increased amount of thyroid hormone for your body to continue to work properly. Discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Pregnancy: Estrogen should not be used during pregnancy. If you become pregnant while taking this medication, contact your doctor.

Breast-feeding: Estrogen is not safe for use during breast-feeding. A decision should be made whether to discontinue breast-feeding or to discontinue the medication, taking into account the importance of the medication to the mother.

Children: The safety and effectiveness of this medication have not been established for children.

There may be an interaction between estradiol and any of the following:

• anastrozole
• "azole" antifungals (e.g., ketoconazole, itraconazole, voriconazole)
• barbiturates (e.g., phenobarbital)
• bosentan
• carbamazepine
• celecoxib
• ceritinib
• clarithromycin
• clozapine
• corticosteroids (e.g., hydrocortisone, prednisolone, prednisone)
• dabrafenib
• dehydroepiandrosterone
• diabetes medications (e.g., acarbose, canagliflozin,  glyburide, insulin, lixisenatide, metformin, rosiglitazone, saxagliptin)
• dipyridamole
• efavirenz
• elagolix
• etravirine
• exemestane
• grapefruit juice
• HIV protease inhibitors (e.g., lopinavir, ritonavir, saquinavir)
• lamotrigine
• lenalidomide
• lumacaftor and ivacaftor
• melatonin
• mifepristone
• modafinil
• nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., ibuprofen, naproxen, ketoprofen)
• ospemifene
• phenytoin
• pomalidomide
• primidone
• rifabutin
• rifampin
• ropinirole
• St. John's wort
• somatropin
• tacrolimus
• thalidomide
• theophyllines (e.g., aminophylline, oxtriphylline, theophylline)
• thyroid medications (e.g., levothyroxine, liothyronine)
• tizanidine
• tranexamic acid
• ursodiol
• warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.