Pharmacology · Class
Hormonal contraceptives !
Estrogen plus progestin, or progestin alone: they prevent pregnancy by stopping ovulation and thickening cervical mucus, and treat period problems.
Updated 2026-11-01
What they are
Combined methods (an estrogen such as ethinylestradiol plus a progestin) and progestin-only methods (pills, injections, implants, intrauterine systems, emergency contraception). Besides contraception they treat heavy or irregular periods, acne and the cycle problems of polycystic ovary syndrome.
Mechanism of action
The progestin and the estrogen suppress the hypothalamic and pituitary signals (GnRH, LH and FSH) through negative feedback, so no follicle matures and no ovulation occurs. The progestin also thickens cervical mucus, which blocks sperm, and thins the endometrium.
Target: Progesterone and estrogen receptors (hypothalamus, pituitary, cervix, endometrium)
Drugs in this class
- Ethinylestradiol + levonorgestrelThe classic combined contraceptive pill (estrogen plus progestin): it stops ovulation. Risk of blood clots; not for…Progesterone receptor (PGR) and estrogen receptor
- LevonorgestrelProgestin used alone as emergency contraception (within 3 days), in progestin-only pills, implants and intrauterine…Progesterone receptor (PGR)
Others in the class
- Etonogestrel
- Desogestrel
- Norethisterone
- Medroxyprogesterone acetate
- Drospirenone
Test yourself
Think of the answer, then tap the question to see it.
How do combined hormonal contraceptives prevent ovulation?
Estrogen and progestin suppress GnRH, LH and FSH by negative feedback, so no follicle matures and the LH surge does not occur.
Which serious adverse effect is linked to the estrogen component?
Venous thromboembolism (deep vein thrombosis and pulmonary embolism).
Which two enzyme inducers can make hormonal contraception fail?
Rifampicin, carbamazepine, phenytoin, barbiturates, efavirenz or St John's wort.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - LEVONORGESTREL AND ETHINYL ESTRADIOL kit (DailyMed (U.S. National Library of Medicine), 2026); Ethinyl Estradiol and Norethindrone (Oral Contraceptives): MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.