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Syntest HS Side Effects

Generic name: esterified estrogens / methyltestosterone

Medically reviewed by Last updated on May 23, 2024.

Note: This document contains side effect information about esterified estrogens / methyltestosterone. Some dosage forms listed on this page may not apply to the brand name Syntest HS.

Applies to esterified estrogens / methyltestosterone: oral tablet.


Oral route (Tablet)

Estrogens increase the risk of endometrial cancer; monitor for abnormal vaginal bleeding. Estrogens with or without progestins should not be used for the prevention of cardiovascular disease or dementia. Increased risks of myocardial infarction, stroke, invasive breast cancer, pulmonary emboli, and deep vein thrombosis in postmenopausal women (50 to 79 years) have been reported. An increased risk of developing probable dementia in postmenopausal women 65 years or older has also been reported. This product contains an estrogen and androgen, not a progestin. This combination should not be used during a known or suspected pregnancy.

Serious side effects of Syntest HS

Along with its needed effects, esterified estrogens/methyltestosterone 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 esterified estrogens / methyltestosterone:

More common


Incidence not known

Other side effects of Syntest HS

Some side effects of esterified estrogens / methyltestosterone 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:

Incidence not known

For Healthcare Professionals

Applies to esterified estrogens / methyltestosterone: oral tablet.


General side effects have included increase or decrease in weight, edema, arthralgias, and leg cramps.[Ref]



Frequency not reported: Deep and superficial venous thrombosis, pulmonary embolism, thrombophlebitis, myocardial infarction, stroke, increase in blood pressure[Ref]

In the Women's Health Initiative study (WHI), an increase myocardial infarctions and strokes was observed in women receiving conjugated estrogens compared to placebo; a substudy of the WHI in which women were receiving conjugated estrogen plus progestin, showed an increased risk of coronary heart disease (CHD) events (defined as nonfatal myocardial infarction and CHD death) compared to placebo (37 vs 30 per 10,000 women-years). This increase was observed in year one and persisted. In a clinical trial of secondary prevention of cardiovascular disease (Heart and Estrogen/Progestin Replacement study; HERS) in postmenopausal women with documented heart disease (n = 2,763, average age 66.7 years) use of conjugated estrogens with progestin demonstrated no cardiovascular benefit.[Ref]


The increased risk of breast cancer due to use of estrogens is controversial. Several studies have suggested that long-term estrogen therapy may be associated with a slightly increased risk of breast cancer. Meta analysis of 51 studies (epidemiological data) supports a modest risk increase associated with long-term hormone replacement therapy (HRT).

Follow-up to the Nurses' Health Study of 1992 concluded, however, that there is an increased risk of breast cancer in women taking estrogen replacement therapy and that the risk is not reduced by concurrent use of progestins. (In that study, greater risk was associated with advanced age and prolonged duration of hormonal therapy.)

The Women's Health Initiative (WHI) which enrolled predominantly healthy postmenopausal women (n=27,000) to assess the risks and benefits of using conjugated estrogens 0.625 mg/day alone or with medroxyprogesterone acetate 2.5 mg/day compared to placebo has shown an absolute excess risk of 8 more invasive breast cancers per 10,000 women-years in the group treated with CE/MPA. Observational studies have also reported an increased risk of breast cancer in women using estrogen/progestin, with a smaller increased risk for estrogen alone.

The risk of endometrial cancer among unopposed estrogen users is about 2 to 12- fold greater than in non-users. Most studies have shown no significant increased risk with use for less than 1 year, but an increased risk of 15 to 24-fold with use for 5 to 10 years or more, persisting for at least 8 to 15 years after estrogen therapy is discontinued.[Ref]


Frequency not reported: Ovarian cancer, endometrial hyperplasia, endometrial cancer, breast cancer, increase in abnormal mammograms, hepatocellular carcinomas


Frequency not reported: Hepatocellular carcinoma[Ref]



Frequency not reported: Changes in vaginal bleeding pattern, abnormal withdrawal bleeding or flow, breakthrough bleeding, spotting, dysmenorrhea, increase in size of uterine leiomyomata, vaginitis, including vaginal candidiasis, change in amount of cervical secretion, changes in cervical ectropion, endometrial hyperplasia, premenstrual like syndrome, amenorrhea during and after treatment; cystitis like syndrome


Frequency not reported: Amenorrhea and other menstrual irregularities, clitoral enlargement[Ref]



Frequency not reported: Nausea, vomiting, abdominal cramps, bloating, gallbladder disease, pancreatitis


Frequency not reported: Nausea[Ref]



Frequency not reported: Chloasma or melasma (may persist when drug is discontinued), scalp hair loss, hirsutism, erythema nodosum, hemorrhagic eruptions, erythema multiforme, rash, pruritus


Frequency not reported: Hirsutism, male pattern baldness, acne[Ref]



Frequency not reported: Retinal vascular thrombosis, steepening of corneal curvature, intolerance to contact lenses[Ref]

Nervous system


Frequency not reported: Migraine, dizziness, headache, exacerbation of epilepsy, dementia, chorea


Frequency not reported: Increased or decreased libido, headache, anxiety, depression, generalized paresthesia[Ref]



Frequency not reported: Suppression of clotting factors II, V, VII, and X, bleeding in patients on concomitant anticoagulant therapy, polycythemia[Ref]



Frequency not reported: Urticaria, angioedema, anaphylactoid/anaphylactic reactions


Frequency not reported: Anaphylactoid/anaphylactic reactions.[Ref]



Frequency not reported: Exacerbation of asthma[Ref]



Frequency not reported: Increase or decrease in weight, reduced carbohydrate tolerance, aggravation of porphyria, edema, hypocalcemia, increased triglycerides


Frequency not reported: Retention of sodium, chloride, water, potassium, calcium, and inorganic phosphates; increased serum cholesterol[Ref]



Frequency not reported: Arthralgias, leg cramps



Frequency not reported: Mental depression, nervousness, mood disturbances, irritability



Frequency not reported: Benign hepatic adenomas, hepatic hemangiomas


Frequency not reported: Cholestatic jaundice, alterations in liver function tests, peliosis hepatis



Frequency not reported: Increased levels of thyroxin-binding globulin, breast tenderness, enlargement, pain, nipple discharge, galactorrhea, fibrocystic breast changes


Frequency not reported: Inhibition of gonadotropin secretin, virilization


1. (2008) "Product Information. Estratest (esterified estrogens-methyltestosterone)." Solvay Pharmaceuticals Inc

2. (2008) "Product Information. Estratest H.S. (esterified estrogens-methyltestosterone)." Solvay Pharmaceuticals Inc

3. (2019) "Product Information. Esterified Estrogens-Methyltestosterone (esterified estrogens-methyltestosterone)." Amneal Pharmaceuticals

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.