Letrozole (Femara) for fertility

Letrozole (brand name Femara) is a tablet taken for a few days early in the menstrual cycle to encourage the ovaries to grow and release an egg. It belongs to a group of medicines called aromatase inhibitors. Although it was first developed to treat breast cancer, it is now one of the most widely used medicines for ovulation problems, and in many cases it has become the first choice.

Who letrozole is for

It is mainly for people who do not ovulate regularly, most often because of PCOS. It is also used to grow one or two mature eggs in a timed-intercourse or IUI cycle, including for unexplained infertility. It is not the right tool where the problem is blocked tubes or severe male-factor infertility, because it does nothing for those underlying issues.

How it works

Letrozole is taken as tablets, usually on days 3 to 7 or 5 to 9 of the cycle. It briefly lowers estrogen, which prompts the brain to release more FSH, the hormone that makes a follicle grow. A clinic often checks the response with a short ultrasound, and may add a trigger shot to set the timing of ovulation. Fertilisation then happens naturally or through IUI.

How well it works

In PCOS, letrozole leads to ovulation in most people who take it. Evidence from large trials shows it results in more live births than clomiphene, the older tablet, with a lower chance of a twin pregnancy. It is usually tried for a few cycles. If several cycles do not work, a clinic will look at injections or IVF.

Side effects

Side effects are generally mild and short-lived: tiredness, hot flushes, headache, or breast tenderness for the days it is taken. Because it clears the body quickly, it tends to be gentler on the lining of the womb than clomiphene. Worries raised some years ago about birth defects have not been borne out by later research.

Letrozole in India

Letrozole is widely available and inexpensive, often only a few hundred rupees for a cycle's worth of tablets. It is a basic treatment that a gynaecologist or a Level 1 registered clinic can prescribe and monitor. You can check a clinic's registration in our directory, and our what registration means page explains the levels.

Questions worth asking

Useful questions before starting include: how many cycles will we try before changing the plan, will you scan to check how I respond, will I need a trigger shot, and what is a realistic chance for someone my age. Our questions to ask your clinic guide has more.