Letrozole for IUI: How It Works and Potential Side Effects

When you and your loved one decide to try fertility treatments such as intrauterine insemination (IUI) to conceive, your fertility specialist may recommend medications to improve your chances. One such medication is letrozole, a drug originally developed to slow and stop the growth of breast cancer in menopausal women.

So how does this cancer medication help with IUI? Let's take a closer look at how letrozole works and how it can assist in your fertility journey.

What is letrozole?

Letrozole is a hormonal therapy drug designed to suppress oestrogen production in your body. It works by blocking an enzyme called aromatase, which converts male hormones (androgens) into female hormones (oestrogens).

This hormonal conversion process occurs in women of all ages but becomes the primary source of oestrogen in menopausal women because the ovaries no longer produce these hormones. 

So, if a menopausal woman has a breast cancer that happens to use oestrogen to fuel its growth (known as oestrogen receptor-positive cancer), letrozole is likely to be prescribed to prevent further growth of the cancer.

How does letrozole work in IUI?

Letrozole works by lowering oestrogen levels in your body. As oestrogen drops, your brain will respond by releasing follicle-stimulating hormone (FSH). This hormone stimulates your ovaries to grow and mature eggs within the follicles.

When the follicles are mature, a trigger shot may be given to release the egg (ovulation), making timing for IUI more predictable.

Letrozole is commonly used as a first-line treatment for ovulation induction in IUI, often replacing clomiphene citrate (Clomid). This is because letrozole is safer and more effective while also maintaining a more natural oestrogen environment and is less likely to cause thinning of the uterine lining when compared with Clomid.

During your IUI treatment, your fertility specialist may prescribe letrozole to:

• Stimulate ovulation if you don't ovulate regularly

• Time ovulation to align precisely with IUI insemination

• Enhance pregnancy success if you experienced unexplained infertility

• Increase the number of mature follicles, resulting in more eggs being released and improving the chance of conception.

Who should consider letrozole for IUI?

Letrozole is usually recommended if you:

• Have polycystic ovary syndrome (PCOS) or experience irregular ovulation

• Have not responded well to Clomid

• Undergoing IUI treatment due to unexplained infertility

• Concerned about Clomid's effects on cervical mucus or the uterine lining

• Want to reduce the risk of multiple pregnancies, as letrozole typically produces fewer mature follicles than other injectable hormones

For more information about IUI with letrozole and to explore other fertility medication options, schedule an appointment with Thomson Fertility Centre. Our fertility specialists can help diagnose your condition and determine the most suitable treatment options for you.

How is letrozole administered?

If you're prescribed letrozole, it is administered orally. The tablets come in 2.5-milligram dosages. Your doctor will guide you on when to take letrozole, but you’ll likely begin taking this medication somewhere between the second and sixth day of your menstrual cycle.

Common fertility dosages include 2.5 mg, 5 mg, or 7.5 mg daily for five consecutive days, depending on your fertilitiy conditions. Your specialist may also recommend timed intercourse following the five-day course to optimise conception chances.

IUI success rates with letrozole

Success rates for IUI treatment with letrozole vary based on your age, underlying fertility diagnosis, and individual cycle characteristics. But in general:

• IUI with letrozole results in pregnancy rates of 10-20% per cycle, which is higher than natural cycle IUIs for many couples.

• If you're experiencing PCOS, letrozole has been shown to be more effective than Clomid in achieving ovulation and pregnancy.

• In cases of unexplained infertility, letrozole often improves cycle predictability and promotes better endometrial development than Clomid.

Cumulative success increases with multiple IUI cycles, especially when combined with ovulation induction.

Are there any side effects of letrozole?

Letrozole is generally a well-tolerated fertility medication, but as with any drug, you may experience some side effects. Most of these are mild and will go away on their own. Some common side effects include:

• Hot flashes

• Headaches

• Fatigue

• Dizziness

• Mood swings

• Mild bloating or abdominal discomfort

However, there are less common but more serious side effects, such as:

• Ovarian hyperstimulation syndrome (OHSS), though the risk is lower than with injectable hormones.

• Multiple pregnancy (twins or more), though less common than with other fertility medications.

But note that these fertility medications should only be used under medical supervision. This medication is not recommended if you have liver disease, undiagnosed vaginal bleeding or are currently pregnant.

You should also tell your doctor about any other medications, hormonal birth control or supplements you are currently taking. This is because letrozole can interact with medications that affect oestrogen.

To ensure that letrozole is suitable for your IUI cycle, schedule an appointment with a fertility specialist at Thomson Fertility Centre. Our specialist can perform further diagnosis and provide you with a personalised recommendation.

FAQ

Can letrozole be used alongside other fertility medications?

Are there long-term risks to using letrozole for fertility?

Current studies suggest that there are no known long-term risks when letrozole is used for a limited number of cycles in fertility treatment. When used properly, it does not appear to increase the risk of cancer or long-term hormonal disruption.

What should I do if I experience side effects?

How many days do you take letrozole for IUI?

Letrozole is typically taken once daily for five days, starting between the second and sixth day of your menstrual cycle. The dosage usually ranges from 2.5 mg to 7.5 mg, depending on your fertility needs. Your fertility doctor will advise you on the exact timing and dosage.

Does letrozole increase the chances of pregnancy?

Is there a risk of birth defects with letrozole?

Recent studies have found no increased risk of birth defects or foetal abnormalities when letrozole is used for fertility treatment. This is especially true when the medication is taken only before conception and is not continued during pregnancy.

The information provided is for general guidance only and should not be considered as medical advice. For a personalised fertility consultation and tailored advice,schedule an appointment withThomson Fertility Centre today.