Ethinylestradiol
A synthetic estrogen used with a progestogen in combined contraceptive pills to stop ovulation and prevent pregnancy.
Also called ethinyl estradiol (US name) or EE (abbreviation).
Drug card
- Class
- Estrogen
- How it works
- Activating estrogen receptors and suppressing LH and FSH release
- Used for
- Contraception (combined pill)
- Heavy periods
- Painful periods
- Acne
- Known for
- Blood clots in a leg or lung (DVT, pulmonary embolism)
- Breakthrough bleeding or spotting
- Its name
- -estr- means an estrogen
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does ethinylestradiol work?
Ethinylestradiol is a semisynthetic estrogen that binds estrogen receptors and switches on estrogen-responsive genes. Together with the progestogen in a combined pill it suppresses pituitary LH and FSH, so no egg is released, while changes to cervical mucus and the endometrium add to the effect. In the liver it raises binding proteins such as SHBG.
Uses
What is ethinylestradiol used for?
- Contraception (combined pill)
- Heavy periods
- Painful periods
- Acne
- Endometriosis symptoms
- Symptoms of PCOS (PMOS)
Side effects
Side effects of ethinylestradiol
- Blood clots in a leg or lung (DVT, pulmonary embolism)Known forSerious
- Breakthrough bleeding or spottingKnown for
- Heart attack and stroke (rare; more likely in smokers)Serious
- Nausea
- Headache
- Breast tenderness
- Mood changes and depression
- Raised blood pressure
- Gallbladder disease
- Cholestatic jaundiceSerious
- Brown patches on the face (chloasma)
- Slightly higher breast and cervical cancer riskSerious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Contraindicated in smokers over 35 and with past clots, migraine with aura, uncontrolled hypertension or breast cancer.
- Enzyme inducers such as rifampicin, carbamazepine and St John's wort can cause contraceptive failure.
- Stop it at least 4 weeks before major surgery or long immobilization, to lower the clot risk.
- It raises thyroxine-binding globulin, so people on thyroid replacement may need a higher dose.
Good to know: Clot risk is highest in the first year of use and again on restarting after four weeks or more without it.
Remember it
A way to remember it
CLOTS
- C
- Combined pills: not for smokers over 35
- L
- Liver disease: avoid
- O
- Osteoporosis prevention after menopause
- T
- Thromboembolism: DVT and pulmonary embolism
- S
- Stroke and heart attack
Clots are the first risk to remember with estrogens; the letters add who must avoid them and one of their benefits.
Written for biofideX
Its name
-estr- means estrogen
Ethinylestradiol and estradiol carry it. Watch for -gestr- in progestogens (levonorgestrel) and -estrant in estrogen receptor blockers (fulvestrant).
- Every drug name stem
Its class
Estrogens
Estrogens bind estrogen receptors, nuclear receptors (two types are known) that switch on estrogen-responsive genes in tissues such as the uterus, breast, bone and liver. They also feed back on the pituitary to cut LH and FSH release; with a progestogen this stops ovulation. In menopause they replace the estrogen the ovaries no longer make, easing symptoms and protecting bone.
Easily mixed up with progestogens and selective estrogen receptor modulators.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Levonorgestrel and ethinyl estradiol tablets: label (DailyMed)
- Ethinyl Estradiol (NCI Thesaurus)
- What is the combined pill? (NHS)
- Side effects and risks of the combined pill (NHS)
- Who can take the combined pill (NHS)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Reproductive and urinary health
Ethinylestradiol is one of 9 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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