Ethinyl Estradiol Side Effects
Cardiovascular
Cardiovascular side effects have included studies suggesting that unopposed estrogen therapy decreased the risk of coronary heart disease by as much as 35%. Combination therapy with a progestin may have also decreased coronary risk. However, the extent of risk reduction with combination therapy has not been determined. Data are available that suggest combination therapy does not reduce the overall rate of coronary heart disease in postmenopausal women with established coronary disease.[Ref]
The effects of estrogen therapy in reducing cardiovascular risk are thought to be related to beneficial alterations in lipid profiles in treated women. The reported effects of estrogens on cardiovascular activity are variable. Alterations in lipid profiles in treated women are thought to be responsible for reducing cardiovascular risks. Data have suggested estrogen use may increase blood pressure, particularly in patients receiving high doses, decrease blood pressure, or result in no change. In addition, noncontraceptive use of estrogens in young women (particularly smokers) may substantially increase the risk of nonfatal myocardial infarction. Other studies have concluded that no increased risk of myocardial infarction exists.[Ref]
Dermatologic
Dermatologic side effects have included chloasma or melasma. Resolution has not occurred in all cases following discontinuation of estrogen therapy. Scalp hair loss, hirsutism, erythema nodosum, and hemorrhagic eruptions have occurred.[Ref]
Endocrine
Endocrine side effects have included increased levels of thyroxin-binding globulin, leading to an increase in total thyroid serum levels and a decrease in resin uptake of T3. Free thyroid hormone levels remain unchanged. Decreased fasting plasma glucose levels have been reported.[Ref]
Gastrointestinal
Gastrointestinal side effects have included frequent reports of nausea and vomiting. Some studies have demonstrated a 2 to 4 fold increase in gallbladder disease in postmenopausal women taking estrogen therapy.[Ref]
Rarely, cases of oral pigmentation and ischemic colitis have been reported.[Ref]
General
General side effects have included fluid retention and mastodynia. Alterations in libido have occurred.[Ref]
Genitourinary
Genitourinary side effects have included abnormal uterine bleeding. This must be carefully distinguished from bleeding related to endometrial carcinoma. In addition, estrogens may increase the size of preexisting uterine leiomyomata. Several cases of pseudoincontinence (excessive vaginal discharge perceived by patients as urinary incontinence) have been reported in premenopausal who have undergone hysterectomy-oophorectomy and received post-operative estrogens.[Ref]
Hematologic
Hematologic side effects have included hypercoagulability.[Ref]
Hepatic
Hepatic side effects have included rare cases of focal nodular hyperplasia, liver cell adenomas, hepatic hemangiomas and well-differentiated hepatocellular carcinomas. Aggravation of porphyria has been reported.[Ref]
Many of the reports of hepatic tumors have occurred in women taking long-term oral contraceptives. However, some tumors have been reported in women taking isolated estrogen therapy.[Ref]
Hypersensitivity
Hypersensitivity side effects have include anaphylaxis.[Ref]
Metabolic
Metabolic side effects have included generally favorable alterations in plasma lipid profiles. Specifically, increased HDL and decreased cholesterol and LDL levels have occurred. Estrogen therapy may lead to an increase in serum triglyceride levels resulting in pancreatitis in patients with familial lipoprotein metabolic defects. Metabolic adverse effects such as hypercalcemia have occurred in patients with breast cancer and bone metastases.[Ref]
Nervous system
Nervous system side effects have included migraine, dizziness, and mental depression. A case of chorea has been reported in association with conjugated estrogen therapy.[Ref]
Ocular
Ocular side effects have included alterations in corneal curvature and contact lens discomfort.[Ref]
Oncologic
Oncologic side effects have included an increased risk of endometrial carcinoma in patients with an intact uterus on unopposed estrogen therapy.[Ref]
A number of studies have suggested that the risk of endometrial carcinoma is removed (or delayed) by the administration of progestins in combination with estrogen therapy. 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). One study of Swedish women has reported that a 10% increase in the relative risk of breast cancer may occur and that the risk is related to increasing duration of estrogen therapy. In that study, women with more than nine years of estrogen use had a 70% greater relative risk of breast cancer than controls. That study, however, examined use of a variety of estrogen preparations of which estradiol was the most frequently prescribed. In addition, women who took progestins did not demonstrate a decreased risk of breast cancer and may even have been at higher risk. The Toronto Breast Cancer Study has reported that women who receive unopposed conjugated estrogens for less than 15 years are not at increased risk of breast cancer. In that study, an increase in the risk of breast cancer for women who used conjugated estrogens for more than 15 years was not ruled out. The Case-Control Surveillance Study has reported that there is “no evidence that the use of unopposed conjugated estrogens increases the risk of breast cancer, even after long duration of use or long latent intervals, but the possibility of a modest increase (less than a doubling) could not be excluded.” 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.) A study of middle-aged women in the Puget Sound area concluded that “on the whole, the use of estrogen with progestin HRT [hormone replacement therapy] does not appear to be associated with an increased risk of breast cancer in middle-aged women.” A prospective cohort study (11 years) of 37105 women by Gapstur et al evaluated the histology of the breast cancer in women who ever used HRT. No association was found between duration of ever HRT use and the incidence of ductal carcinoma in situ or invasive ductal/lobular carcinoma. The duration of ever HRT use was associated with risk of invasive carcinoma with a favorable prognosis (relative risk (RR) = 1.81, 95% confidence interval (CI), 1.07 to 3.07 for HRT use less than or equal to 5yrs and RR = 2.65, CI, 1.32 to 5.23 for HRT use > 5yrs, p = 0.005). The relative risks of invasive carcinoma with a favorable prognosis for current users (adjusted for age and other risk factors) was 4.42, CI, 2.00 to 9.76 for less than or equal to 5yrs and 2.63, CI, 1.18 to 5.89 for > 5yrs. Risk of invasive ductal or lobular carcinoma for current users less than or equal to 5yrs was RR = 1.38, CI, 1.03 to 1.85.[Ref]
Other
Other side effects have included fibrocystic breast disease.[Ref]
Psychiatric
Psychiatric side effects have included case reports of rapid mood cycling in patients with severe depression.[Ref]