What are the Best Fertility Medications?

Fertility medications are among the most effective tools in reproductive medicine — when matched to the right diagnosis. The "best" fertility medication is always the one that addresses your specific physiological barrier to conception. Understanding how each medication works, what it's indicated for, and what it doesn't treat is essential for evaluating whether a prescribed protocol actually makes sense for your situation.

Clomiphene Citrate (Clomid)

Clomiphene is the most widely prescribed ovulation induction medication and has been in use since the 1960s. It works by blocking estrogen receptors in the hypothalamus, which causes the pituitary to increase FSH production, stimulating follicle development. It is indicated primarily for anovulatory women — those who don't ovulate regularly — and is most effective in women with PCOS or hypothalamic amenorrhea who are producing adequate estrogen.

Clomiphene is inexpensive, oral, and generally well tolerated. Its main limitations include anti-estrogenic effects on the endometrium (which can thin the uterine lining and reduce implantation rates), poor cervical mucus production, and a meaningful percentage of women who don't respond to it (particularly those with high body weight or severe PCOS). Typical success rates are 10–20% live birth per cycle, with cumulative rates of approximately 40–50% after 6 cycles in appropriately selected patients.

Letrozole (Femara)

Letrozole is an aromatase inhibitor originally developed for breast cancer treatment. It works by blocking estrogen synthesis, which triggers a compensatory increase in FSH from the pituitary. Unlike clomiphene, letrozole does not have anti-estrogenic effects on the endometrium or cervical mucus, making it the preferred agent for many ovulation induction cases. Multiple randomized controlled trials — including the landmark NICHD study — have demonstrated higher live birth rates with letrozole versus clomiphene in women with PCOS. It has now become first-line ovulation induction therapy for PCOS at most major reproductive centers.

Gonadotropins (FSH and LH Injections)

Injectable gonadotropins — recombinant FSH, LH, or combinations — directly stimulate the ovaries to develop follicles. They bypass the hypothalamic-pituitary axis entirely and are used in women who don't respond to oral agents, in IUI and IVF protocols requiring controlled ovarian hyperstimulation, and in women with hypogonadotropic hypogonadism (absent or very low FSH/LH production). They are significantly more effective than oral agents but also more expensive (often $1,000–$6,000 per cycle for medications alone), require monitoring via ultrasound and bloodwork, and carry a meaningful risk of ovarian hyperstimulation syndrome (OHSS).

Metformin

Metformin is an insulin sensitizer, not a fertility medication per se, but it plays an important role in PCOS management. By reducing insulin resistance, it lowers androgen production from the ovaries, which allows ovulation to resume in many women with PCOS. It is often used as an adjunct to clomiphene or letrozole in insulin-resistant PCOS and has been shown to reduce miscarriage risk in PCOS patients when continued into early pregnancy. Its primary fertility indication is insulin-resistant PCOS with anovulation.

Progesterone Supplementation

Progesterone is prescribed in luteal phase support protocols — typically after IUI, IVF embryo transfer, or in women with documented luteal phase deficiency. It supports endometrial preparation for implantation and is often continued through the first trimester. Oral micronized progesterone (Prometrium) and vaginal progesterone (Crinone, Endometrin) are the most common forms; intramuscular injections are used in IVF where higher serum levels are required.

HCG (Human Chorionic Gonadotropin)

HCG injections are used in two ways: as a trigger shot to induce final egg maturation and ovulation at a precise time (typically 36 hours before IUI or egg retrieval), and as low-dose luteal phase support in some protocols. As a trigger, it mimics the LH surge and ensures ovulation predictability. It is a near-universal component of monitored fertility treatment cycles.

What Medication Can't Fix

Fertility medications address ovulation timing and stimulation, hormone levels, and assisted reproduction protocols. They do not address egg quality, sperm quality (except for specific male infertility medications), tubal obstruction, uterine structural issues, or the metabolic and nutritional patterns that underlie many fertility challenges. For most patients, medication is most effective when combined with optimized nutrition, supplement protocols matched to their biology, and appropriate lifestyle modifications — all of which affect the quality of the eggs and sperm that medications are stimulating.

Take the Conceivable quiz to understand which biological factors may be influencing your fertility outcomes and which interventions — medical and nutritional — are most relevant for your situation.

Written by Kirsten Karchmer, reproductive medicine practitioner with 25 years of clinical experience and 10,000+ credited pregnancies, and author of The Road to Better Fertility.