Letrozole and clomiphene citrate (commonly known as Clomid) are oral tablets that bring on ovulation. For women with PCOS, current evidence shows that letrozole works better than clomiphene - with higher ovulation and live-birth rates, fewer side effects, and slightly fewer twins. Both cost well under ₹1,000 per cycle in India. The right choice depends on your diagnosis and how you have responded in the past, not on any one tablet being universally superior.
Both are inexpensive tablets taken for about five days early in the menstrual cycle to encourage the ovaries to release an egg. They reach the same goal by different routes. Clomiphene citrate is a selective estrogen receptor modulator (SERM): it blocks estrogen receptors in the brain, which “tricks” the pituitary gland into releasing more follicle-stimulating hormone (FSH, the hormone that grows egg-containing follicles). Letrozole is an aromatase inhibitor: it briefly lowers the body’s estrogen by blocking the enzyme that makes it, and the brain responds by producing more FSH. The practical difference is that letrozole clears the body quickly, whereas clomiphene lingers - which matters for the womb lining, as explained below.
This table is the quickest way to see how the two compare. The figures for twins come from the largest head-to-head trial in PCOS (described in the next section).
The headline - “letrozole is better” - is true, but it is specific to PCOS, and being precise about that is the honest way to use it. The landmark double-blind trial (Legro and colleagues, published in the New England Journal of Medicine in 2014, involving 750 women with PCOS) found that letrozole produced higher cumulative ovulation (about 62% vs 48%) and higher live-birth rates (about 28% vs 19%) than clomiphene over up to five cycles. Twin pregnancies trended lower with letrozole (around 3% vs 7%), and there were no higher-order multiples with either. Indian studies in PCOS point the same way, which matters because PCOS in Indian women is often linked to insulin resistance and a higher chance of not responding to clomiphene.
The important caveat: this clear advantage is for PCOS. In unexplained infertility, a large separate trial found that letrozole did not outperform clomiphene (and performed slightly worse), so “letrozole is best” should not be stretched to every situation. For ovulation problems caused by PCOS, letrozole is the evidence-based first choice; beyond PCOS, the two are more evenly matched, and the decision is individual.
Both tablets are generally well tolerated, and side effects are usually mild and temporary. The typical pattern is:
• Clomiphene: more likely to cause hot flushes and mood changes, and - because it lingers and blocks estrogen throughout the body - it can sometimes thin the womb lining and thicken cervical mucus, which is one reason it is not ideal for everyone.
• Letrozole: clears quickly and usually preserves a healthy lining; its side effects tend to be fatigue, dizziness, mild joint aches, and headaches.
The most-searched worry deserves a direct, honest answer. Years ago, a small 2005 report raised a concern that letrozole might increase birth defects, and this drove caution (and, in India, a regulatory ban). Larger, better studies since - including the 2014 trial above - have not found an increased risk of congenital anomalies with letrozole, and its very short half-life means it is largely gone from the body before pregnancy begins. On current evidence, letrozole is considered safe for ovulation induction; the early scare was not borne out.
Being moved from one tablet to another is common and usually a sign that the plan is being tailored, not that something has gone wrong. The typical reasons are:
• Clomiphene resistance: the ovaries do not ovulate even after the dose is increased - letrozole often works where clomiphene has not.
• A thin womb lining on clomiphene: letrozole tends to preserve the lining, which can improve the chance of implantation.
• Several ovulatory cycles without pregnancy: switching is one option before escalating to more intensive treatment.
• A PCOS diagnosis: given the evidence, many specialists now start with letrozole in PCOS rather than waiting for clomiphene to fail.
Both are once-daily tablets, usually taken for five days early in the cycle (commonly days two to six). The starting dose is kept low and may be increased in a later cycle if there is no ovulation - always under your specialist’s guidance, with a scan to check the response. The exact dose is individual, so self-adjusting or sourcing tablets without monitoring is not advisable.
As a general rule, oral ovulation tablets are tried for a limited number of ovulatory cycles - usually no more than about six - before reassessing. If you are ovulating well on the tablet but not conceiving after a few cycles, it is time to review the wider picture (tubes, sperm, age) and consider the next step, such as IUI or IVF, rather than repeating the same tablet indefinitely.
The tablets themselves are among the least expensive parts of fertility treatment. Both are widely available generics, and a single cycle’s tablets typically cost well under ₹1,000 - often only a few hundred rupees. The higher cost in a medicated cycle is usually the monitoring (the ultrasound scans and any blood tests) rather than the tablet.
Because the medicine cost is so low, price is rarely the deciding factor between the two tablets - the choice is clinical, based on your diagnosis and response.
Yes, letrozole is available and routinely used for ovulation induction in India today - but it has a notable regulatory history worth knowing. Letrozole was first approved for ovulation induction in India in 2006. In 2011, the drug regulator suspended its use for fertility, largely on the back of the older birth-defect concern. That suspension was challenged, and in 2017, the Union Health Ministry revoked the ban on letrozole for induction of ovulation. It is now widely prescribed and is recommended as the first-line tablet for ovulation in PCOS by major fertility guidelines. In short: once contested, now mainstream and evidence-backed.
If any of these apply, book a fertility consultation with a Cloudnine reproductive medicine specialist to choose the right tablet and plan. You can also read more about PCOS and fertility and how IUI and IVF compare.