Fertility drugs are prescription medications that either induce ovulation or stimulate several eggs to mature in one cycle, and they work. In a 750-woman randomised trial, cumulative live birth over five cycles reached 27.5% with letrozole versus 19.1% with clomiphene — NEJM 2014.
The same trial showed why the choice matters — clomiphene produced twins in 7.4% of pregnancies and letrozole in 3.4%. There is no single “fertility drug.”
There are at least six classes, with different mechanisms, different success rates and very different risks. The gap between the cheapest pill and the strongest injection is where most treatment decisions actually happen.
Sources for this article are randomised trials and Cochrane systematic reviews indexed in PubMed. They include the NICHD PPCOS II and AMIGOS trials published in the New England Journal of Medicine, plus Cochrane reviews of aromatase inhibitors and gonadotropins.
The article also draws on American Society for Reproductive Medicine, ASRM practice guidelines covering unexplained infertility and ovarian hyperstimulation syndrome, and on FDA-approved product labelling. It was compiled by the ProIVF Medical Editorial Team and reviewed by our Medical Advisory Board.
ProIVF does not sell medication and has no commercial relationship with any pharmaceutical manufacturer.
What Are Fertility Drugs, and What Can They Actually Do?
Fertility drugs act on the hormonal signalling that controls egg maturation and release. They do not create eggs, and they do not fix blocked tubes or severe male factor infertility.
Two mechanisms cover most of the field. Ovulation-induction drugs restore a monthly ovulation signal in women who ovulate rarely or not at all, usually by adjusting oestrogen feedback to the pituitary. Controlled ovarian stimulation drugs push a normal cycle to mature several follicles at once, which is the basis of intrauterine insemination and IVF.
That distinction matters because the same drug can be first-line in one situation and inappropriate in another. Our overview of when IVF is used explains which diagnoses need stimulation rather than induction.
How Many Types of Fertility Drugs Are There?
Six classes account for nearly all prescriptions, and they differ more in mechanism than in brand name.
| Class | Examples | Route | Main use |
|---|---|---|---|
| Selective oestrogen receptor modulator (SERM) | Clomiphene citrate, tamoxifen (off-label) | Oral | First-line ovulation induction |
| Aromatase inhibitor | Letrozole | Oral | First-line ovulation induction, especially in PCOS |
| Gonadotropins | Recombinant FSH, urinary FSH, human menopausal gonadotropin (hMG) | Injection | Controlled ovarian stimulation for IUI and IVF |
| Insulin sensitiser | Metformin | Oral | Adjunct in PCOS with insulin resistance |
| Dopamine agonist | Bromocriptine, cabergoline | Oral | Ovulation restored by lowering prolactin |
| Adjuncts | hCG trigger, progesterone | Injection, vaginal or oral | Timing ovulation and supporting the luteal phase |
The four that patients ask about most — clomiphene, letrozole, gonadotropins and metformin — have the best head-to-head data, and each is covered below.
Which Oral Fertility Drug Works Better, Clomiphene or Letrozole?
Letrozole produces more live births than clomiphene in polycystic ovary syndrome. The margin is consistent across a large randomised trial and a Cochrane review.
In PPCOS II, 750 women with PCOS were randomised to letrozole or clomiphene for up to five cycles. Cumulative live birth was 27.5% (103/374) with letrozole versus 19.1% (72/376) with clomiphene (P=0.007; rate ratio 1.44, 95% CI 1.10–1.87) — NEJM 2014. Cumulative ovulation per cycle was 61.7% versus 48.3% (P<0.001).
A 2022 Cochrane review pooling 41 randomised trials and 6,522 women reached the same direction with higher precision. Live birth odds ratio was 1.72 (95% CI 1.40–2.11), with a number needed to treat of 10. Ovarian hyperstimulation syndrome occurred in 0.5% of both arms — Cochrane 2022.
Dosing is straightforward for both drugs.
- Clomiphene citrate: the label regimen is 50 mg daily for five days, usually starting on cycle day 5. If ovulation does not occur, the dose escalates to 100 mg and then 150 mg — FDA labelling.
- Letrozole: 2.5–5 mg daily for five days starting on cycle day 3, 4 or 5; 2.5 mg is the usual first dose in PCOS.
- Both are usually monitored with a mid-cycle ultrasound or a day-21 progesterone test, which is where the real cost often sits.
Our drug-specific guides cover the detail: clomiphene for fertility and letrozole for fertility.
Do Gonadotropin Injections Improve Live Birth Enough to Justify Them?
Gonadotropins do produce more live births than oral drugs, but the gain is smaller than most patients expect and the multiple-pregnancy risk is much larger.
A meta-analysis of eight trials covering 2,989 patients and 6,590 cycles found that gonadotropins raised the relative risk of live birth by just 1.09 over oral agents. The multiple-gestation relative risk was 1.06 — Fertil Steril 2020. Protocols with lax cancellation criteria or higher doses pushed that risk to 1.20 and 1.15.
The AMIGOS trial randomised 900 ovulatory women with unexplained infertility to up to four cycles of gonadotropin, clomiphene or letrozole — NEJM 2015. Live birth per cycle was 32.2% with gonadotropin, 23.3% with clomiphene and 18.7% with letrozole.
The trade-off appears in the multiple-gestation rate among ongoing pregnancies with fetal heart activity: 32% with gonadotropin, 9% with clomiphene and 13% with letrozole. Every multiple in the clomiphene and letrozole groups was a twin, whereas gonadotropin treatment produced 24 twins and 10 triplets.
A 2025 Cochrane review added a further caution. Against continued clomiphene, gonadotropins produced a live birth RR of 1.24 (95% CI 1.05–1.46, 661 women). Clinical pregnancy rose (RR 1.31, 95% CI 1.13–1.52), but miscarriage may also increase (RR 2.23, 95% CI 1.11–4.47) — Cochrane 2025.
“For most couples, the best initial therapy is a course (typically 3 or 4 cycles) of ovarian stimulation with oral medications and intrauterine insemination (OS-IUI) followed by in vitro fertilization for those unsuccessful with OS-IUI treatments.” — ASRM Practice Committee guideline on unexplained infertility, Fertility and Sterility, 2020
That sequencing is the single most useful cost-control decision in fertility treatment. It is why our IUI procedure guide treats oral stimulation plus insemination as the default first move.
What About Ovarian Hyperstimulation Syndrome?
Ovarian hyperstimulation syndrome (OHSS) is the most serious drug-related complication, and its risk is concentrated in gonadotropin cycles rather than oral ones.
OHSS rates were 0.5% in both the letrozole and clomiphene arms of the Cochrane analysis — effectively identical and low. Gonadotropin cycles carry the real risk, which is why the ASRM published a dedicated guideline on preventing moderate and severe OHSS — Fertil Steril 2024. The practical protections are a lower starting dose, a GnRH antagonist trigger instead of hCG where appropriate, and freezing all embryos rather than transferring in the stimulated cycle.
Do Fertility Drugs Cause Twins? The Real Numbers
They raise the risk. How much depends almost entirely on how many follicles mature, which is why the honest answer is “sometimes, and less than you think.”
FDA labelling for clomiphene reports multiple pregnancy in 7.98% of reported pregnancies: twins 6.9%, triplets 0.5%, quadruplets 0.3% and quintuplets 0.1%. In PPCOS II the twin rate was 7.4% with clomiphene versus 3.4% with letrozole. In a Cochrane pooled analysis, multiple pregnancy was 2.2% with SERMs such as clomiphene versus 1.6% with letrozole.
Gonadotropins are the outlier. In AMIGOS, 32% of ongoing gonadotropin pregnancies were multiples, including 10 triplet gestations.
The reason this matters more than the twin rate itself is outcome. Clomiphene labelling data show survival to live birth of 98.16% for singleton pregnancies versus 83.25% for multiple pregnancies. Counting miscarriage, stillbirth and neonatal death together, overall survival in multiple gestations was 73%.
Can You Ask for Fertility Drugs to Have Twins?
You can ask, and a responsible clinic will decline to aim for it, because twin pregnancy is a complication rather than a bonus.
The data above are the argument: a 15-percentage-point drop in survival to live birth, plus higher rates of preterm delivery and pre-eclampsia. A NICU stay alone can cost more than the fertility treatment itself. Where a clinic can control follicle number, that is the standard of care. Cancelling a cycle with too many mature follicles, or converting to IVF with single embryo transfer, are the usual routes.
Is Metformin a Fertility Drug?
Metformin is not an ovulation-induction drug, but it can improve ovulation and pregnancy rates in women with PCOS and insulin resistance.
A Cochrane review found that metformin compared with placebo may improve live birth (OR 1.59, 95% CI 1.00–2.51, 4 studies, 435 women). It did improve clinical pregnancy (OR 1.93, 95% CI 1.42–2.64) and ovulation (OR 2.55, 95% CI 1.81–3.59). Gastrointestinal side effects were more common (OR 4.76, 95% CI 3.06–7.41) — Cochrane 2017.
Adding metformin to clomiphene did not conclusively improve live birth (OR 1.21, 95% CI 0.92–1.59).
Are There Over-the-Counter Fertility Drugs?
No. Every drug that induces ovulation or stimulates the ovaries in the classes above requires a prescription.
Those drugs carry real risks — OHSS, multiple pregnancy and, with unmonitored use, undiagnosed ectopic pregnancy.
What is sold over the counter are supplements, which are regulated as food rather than medicine. A systematic review of ingredients in popular male fertility supplements found that most lacked adequate evidence to support their claims — Urology 2020. Supplements are not drugs, and “natural fertility booster” is a marketing category rather than a pharmacological one. Our fertility supplements guide covers what the evidence does and does not support.
How Much Do Fertility Drugs Cost?
Cost spans two orders of magnitude, from a few dollars for a five-day oral course to several thousand for a gonadotropin cycle. Monitoring, not medication, is often the larger line item.
| Regimen | Typical drug cost | Notes |
|---|---|---|
| Letrozole 2.5 mg, five days | 10–50 USD | Generic; the cheapest effective option |
| Clomiphene 50 mg, five days | 10–60 USD | Generic; cost is not the differentiator |
| Metformin, one month | 4–30 USD | Generic |
| Gonadotropin injections, one cycle | 1,000–3,000+ USD | Dose-dependent; brand and country vary widely |
| hCG trigger | 50–150 USD | Single dose |
| Monitoring per cycle | Often exceeds drug cost | Ultrasound and blood tests |
A randomised Dutch cost analysis put the average cost per couple at 1,067 euros for clomiphene versus 1,534 euros for gonadotropins. The incremental cost-effectiveness ratio was 17,044 euros per additional live birth. The full picture, including how countries differ, is in our IVF cost guide.
Real Patients: Three Fertility-Drug Stories
The three accounts below are composite examples built from published trial patterns and typical clinic protocols. No individual patient is identified, and the figures illustrate ranges rather than predicting any specific outcome.
”Three cycles of pills, 340 dollars.”
Texas, age 29, three cycles, 340 USD in medication. She was diagnosed with PCOS after 14 months of irregular cycles.
The first cycle ovulated on 50 mg but did not conceive. The second was escalated to 100 mg, and her mid-cycle ultrasound showed a 6 mm lining, so her doctor added vaginal oestrogen. The third cycle produced two follicles, and she was pulled into an unexpected conversation about multifetal reduction.
“I had budgeted for the pills,” she said. “Nobody told me the ultrasound and the oestrogen were where the money went.” She conceived a singleton on a fourth cycle after metformin was added.
”The injection worked on the first try, and that was the problem.”
Seoul, age 33, one gonadotropin IUI cycle, about 1,400 USD. With unexplained infertility and a normal cycle, she moved straight to injectable stimulation for IUI.
Monitoring showed four mature follicles, and the clinic proceeded. The cycle resulted in a triplet pregnancy that reduced spontaneously to twins, delivered at 33 weeks with six weeks of NICU care.
“Everyone congratulated me,” she said. “I spent the first month terrified, not happy.” Her second attempt used oral letrozole with a strict two-follicle cancellation rule and produced a single baby.
”Nobody would say the word ‘drugs.’”
Warsaw, age 37, six months of supplements, about 600 USD. She spent six months and roughly 600 USD on over-the-counter “fertility boosters” before seeing a reproductive endocrinologist.
That specialist explained her anovulatory cycles needed a prescription, not a supplement. “The website said clinically proven,” she said. “My doctor asked me which clinical trial, and I did not have an answer.” She ovulated on letrozole 2.5 mg in her second monitored cycle and conceived on the third.
FAQ
Q: What is the most effective fertility drug?
It depends on the diagnosis. In polycystic ovary syndrome, letrozole has the strongest evidence, with a live birth odds ratio of 1.72 versus clomiphene across 6,522 women.
For unexplained infertility, gonadotropins produce the most live births per cycle — 32.2% in AMIGOS, against 18.7% for letrozole — but they roughly triple the multiple-pregnancy rate. That is why ASRM recommends starting with oral drugs plus IUI for three or four cycles.
Q: Can I get fertility drugs without a prescription?
No. Clomiphene, letrozole, gonadotropins, metformin and dopamine agonists are all prescription-only, because each requires monitoring for OHSS, multiple pregnancy or an undiagnosed ectopic pregnancy.
Products marketed as over-the-counter fertility boosters are supplements, regulated as food rather than medicine. A 2020 systematic review found most of their ingredients lacked adequate evidence to support their claims.
Q: How long do fertility drugs take to work?
Ovulation usually occurs 5–10 days after the last oral dose, or 24–36 hours after an hCG trigger injection. A cycle is counted as a success or a failure at the point of ovulation or pregnancy testing, so most protocols assess three to six cycles before changing strategy.
Q: Do fertility pills increase the chance of twins?
Yes, modestly. Clomiphene labelling reports multiple pregnancy in 7.98% of reported pregnancies, and PPCOS II recorded twin rates of 7.4% with clomiphene and 3.4% with letrozole.
Gonadotropins are the real outlier, at 32% multiples among ongoing pregnancies in AMIGOS, including 10 triplet gestations.
Q: Is letrozole safer than clomiphene?
They have comparable safety profiles in the trial data. OHSS was 0.5% in both arms of the Cochrane analysis, and miscarriage rates in PPCOS II were close, at 31.8% and 29.1%.
Letrozole’s advantages are efficacy and a lower multiple-pregnancy rate; its disadvantage is that it is used off-label for ovulation induction in some countries.
Q: Can men take fertility drugs?
Yes, in specific diagnoses. Gonadotropins and hCG can restore sperm production in hypogonadotropic hypogonadism, and clomiphene or tamoxifen are used off-label to raise gonadotropin levels.
Hypogonadotropic hypogonadism is a rare condition in which the brain signals the testes too weakly. In one series, hCG plus recombinant FSH induced spermatogenesis in 82.0% of 50 men over a median of 7.5 months — World J Mens Health 2025. Exogenous testosterone is the opposite of a fertility drug here: it suppresses sperm production.
Q: What are the side effects of fertility drugs?
The common ones are dose-related and transient: hot flushes, mood changes, bloating and, with metformin, gastrointestinal upset (OR 4.76 versus placebo). The serious risks are ovarian hyperstimulation syndrome and multiple pregnancy, both concentrated in gonadotropin cycles.
Q: Do I need IVF if fertility drugs do not work?
Not necessarily. The ASRM guideline for unexplained infertility recommends 3 or 4 cycles of oral stimulation with IUI before moving to IVF, and many couples conceive within that window.
What comes after depends on age, ovarian reserve and how many follicles the drugs produced.
Planning Your Fertility Treatment
Three decisions drive both outcome and cost.
- Match the drug to the diagnosis, not to the success story you read. Ovulation induction and controlled ovarian stimulation solve different problems.
- Set a follicle-number rule before you start. Agreeing in advance to cancel or convert a cycle with too many mature follicles is the single most effective way to avoid a high-order multiple pregnancy.
- Count the monitoring, not just the pills. Ultrasound and blood work frequently cost more than the medication itself.
If you want to compare how clinics design stimulation protocols — their cancellation criteria, monitoring intensity and pricing transparency — browse our global hospital directory. You can also contact the ProIVF team for a personalised consultation. How a clinic sets and enforces its follicle rules tells you a great deal about how it manages risk.
This article was written by the ProIVF Medical Editorial Team and reviewed by the ProIVF Medical Advisory Board. It is based on peer-reviewed literature indexed in PubMed. That includes the PPCOS II and AMIGOS trials in the New England Journal of Medicine (2014, 2015) and Cochrane reviews of aromatase inhibitors (2022), gonadotropins (2025) and insulin-sensitising drugs (2017). It also draws on the Fertility and Sterility meta-analysis of oral versus injectable stimulation (2020), ASRM guidelines on unexplained infertility (2020) and OHSS prevention (2024), and FDA-approved labelling. The goal is to provide objective and accurate information for patients.
Medical disclaimer: This article is for educational purposes only and does not replace individualized advice from your reproductive endocrinologist. Fertility drug selection, dosing and monitoring must follow your own physician’s judgment. If you experience severe abdominal pain, rapid weight gain, shortness of breath or reduced urination while taking fertility medication, seek medical care urgently.
Last updated: September 26, 2026
