Ethinylestradiol
Ethinylestradiol is a synthetic oestrogen used in combined oral contraceptives, always paired with a progestogen. The label for one such combination indicates it for use by females of reproductive potential to prevent pregnancy, and MedlinePlus covers the same combination in patient-facing terms. The label carries a boxed warning about cigarette smoking, and its first listed warning is about blood clots.
Ginette-35
Androgen-dependent Acne, Hirsutism
0.035mg + 2mg
Developed to mitigate androgen-related acne and hair growth to support clear skin and target hormone normalisation.
Ortho Tri-cyclen
Contraception, Acne Vulgaris
0,25mg/ 0,035mg
Intended to relieve hormonal fluctuations to support cycle control and target reliable pregnancy prevention.
Key points
- Combined oral contraceptives increase the risk of venous thromboembolic events such as deep vein thrombosis and pulmonary embolism, and the label estimates the rate in females using them at 3 to 9 cases per 10,000 woman years.
- The boxed warning states that cigarette smoking increases the risk of serious cardiovascular events from combined oral contraceptive use, that the risk rises with age and with the number of cigarettes smoked, and that these products are contraindicated in women over 35 who smoke.
- Ethinylestradiol is rapidly and almost completely absorbed from the gastrointestinal tract, but first-pass metabolism in gut mucosa and liver leaves its systemic bioavailability at approximately 43%.
- That first-pass metabolism runs through cytochrome P450 3A4, and CYP3A4 levels vary widely between individuals, which the label says can explain the variation in rates of ethinylestradiol hydroxylation.
Safety specific to ethinylestradiol
Blood clots. This is the warning a combined pill page owes its reader. Use of combined oral contraceptives increases the risk of venous thromboembolic events, meaning deep vein thrombosis and pulmonary embolism. The label lists smoking, obesity and a family history of venous thromboembolism among the risk factors, and puts the rate in females using these products at 3 to 9 cases per 10,000 woman years. It also sets that figure in context: the rates of venous thromboembolism are even greater during pregnancy, and especially during the postpartum period.
Smoking after 35. The boxed warning states that cigarette smoking increases the risk of serious cardiovascular events from combined oral contraceptive use, that this risk increases with age, particularly in women over 35 years of age, and with the number of cigarettes smoked, and that for this reason these products are contraindicated in women who are over 35 years of age and smoke.
Other warnings the label raises. In label order, after thromboembolic and vascular conditions come liver disease including elevated liver enzymes, hypertension, the risk of liver enzyme elevations alongside certain hepatitis C regimens, age-related cardiovascular considerations, gallbladder disease, effects on carbohydrate and lipid metabolism, headache, bleeding irregularities and amenorrhoea, and depression. The label asks that women with a history of depression be carefully observed and that the product be discontinued if depression recurs to a serious degree.
A combined oral contraceptive offers no protection against sexually transmitted infections.
When to seek urgent care
Sudden breathlessness, chest pain, coughing blood, or pain, swelling, warmth or redness in one leg can signal a clot and need emergency assessment. A sudden severe headache, a change in vision or speech, or weakness down one side warrant the same urgency.