Clomiphene vs Levonorgestrel: side-by-side comparison
Clomiphene (Selective estrogen receptor modulator (ovulation induction)) and Levonorgestrel (Synthetic progestin (emergency contraception)) belong to different therapeutic classes and are rarely substitutes for each other. The comparison is useful when a single patient is weighing both options for adjacent or overlapping needs.
| Property | Clomiphene | Levonorgestrel |
|---|---|---|
| Therapeutic class | Selective estrogen receptor modulator (ovulation induction) | Synthetic progestin (emergency contraception) |
| CAS | 911-45-5 | 797-63-7 |
| ATC | G03GB02 | G03AC03 |
| Molecular weight | 405.96 g/mol | 312.5 g/mol |
| Brands with this active ingredient | 1 | 1 |
What they share
Clomiphene and Levonorgestrel share the common regulatory framework for prescription active ingredients, bioequivalence standards for generics, and pharmacist oversight. Beyond that, points in common are limited.
Key differences
Clomiphene acts by a different mechanism than Levonorgestrel, with indications that barely overlap. Comparing the two is useful when a clinician has mentioned both in the same context or the patient wants to understand why one was prescribed instead of the other.
Mechanisms compared
Clomiphene: Clomiphene acts as a competitive antagonist of estrogen receptors at the hypothalamus, blocking the negative feedback that estrogen normally exerts on hypothalamic gonadotropin-releasing hormone production. Levonorgestrel: In emergency contraception, levonorgestrel works primarily by delaying or inhibiting ovulation when taken before the LH surge.
Indications compared
Clomiphene: Clomiphene is approved for the treatment of anovulatory infertility in women with intact pituitary-ovarian function — particularly polycystic ovary syndrome (PCOS) — when other causes of infertility have been excluded or… Levonorgestrel: Levonorgestrel is approved for emergency contraception (single 1.5mg dose), regular oral contraception (combined with ethinylestradiol or as progestin-only), and as the active component of hormonal intrauterine devices f…
Safety profile
Clomiphene: Common adverse effects include hot flashes, mood swings, breast tenderness, ovarian enlargement and visual disturbances (typically reversible on discontinuation). Levonorgestrel: Common adverse effects of emergency contraceptive use include nausea, headache, fatigue, dizziness, breast tenderness and menstrual cycle changes.
Frequently asked questions
Is Clomiphene better than Levonorgestrel? ▾
Clomiphene and Levonorgestrel are not "better or worse" — they treat different things. The sensible question is which fits your specific need.
Can Clomiphene and Levonorgestrel be combined? ▾
Whether they can be combined depends on the indications and the interaction profile of each. If both are in a single prescription, the prescriber has weighed it; in self-medication they should never be combined.
Do they have the same side-effect profile? ▾
No — they belong to different classes and have distinct side-effect profiles. Each has its own prescribing information.
Products with Clomiphene
Products with Levonorgestrel
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.