Ethinyl estradiol is a type of synthetic estrogen derivative primarily used in oral or vaginal contraceptive medications. It is typically combined with another hormone or contraceptive medication, such as drospirenone — a type of progestin — or etonogestrel. It is also occasionally used on its own to treat delayed puberty, regulate menstrual cycles, and treat symptoms of menopause, such as hot flashes, vaginal dryness or bone loss. Pros and cons of using ethinyl estradiol depend on several factors, including the additional hormones included and the medical history of the woman taking it. The medication can help prevent pregnancy, but some women may experience severe side effects while taking it.
When used correctly, ethinyl estradiol combined with drospirenone in an oral medication has about a 99 percent rate of effectiveness in preventing pregnancy. It works by inhibiting ovulation and altering the cervical mucous, which makes it difficult for sperm to gain entry to the uterus. As a final line of defense, if ovulation somehow does occur and the sperm makes it through the altered cervical mucous, the medication also changes the endometrium, making it difficult for a fertilized egg to implant into the uterus.
Vaginal rings made with ethinyl estradiol and etonogestrel are up to 99 percent effective when used correctly, but when allowing for typical use and normal human error, the rate drops to 92.7 percent. The flexible ring is inserted for three weeks, and then removed for a one-week break. The old ring is disposed of and a new ring is inserted for another cycle. It is available only by prescription and must be inserted on the proper day according to the physician’s instructions.
When used to prevent pregnancy, both types of ethinyl estradiol preparations rely on the user’s ability to follow a strict dosing regimen. Missing a pill or forgetting to insert the vaginal ring on the proper day can significantly reduce their effectiveness. Certain medications, particularly antibiotics, can also reduce the preparations' effectiveness.
Common side effects of ethinyl estradiol include vaginal or genital itchiness, abnormal changes in menstrual cycles, and pain during sexual intercourse. Less common side effects may include blurred vision, chest pain, dizziness, and severe uterine cramping. Changes to the breasts, including discharge from the nipples or lumps inside the breasts, can also occur.
Ethinyl estradiol can cause serious complications in some patients, including stroke or heart attack. Alcohol or tobacco use increases the risk of these complications. Women with a history of blood clotting, high blood pressure, or severe kidney disease may not be able to use this medication. The medication may interfere with the effectiveness of bone cancer treatments or worsen cancer of the uterus.