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When is the best time of day to take letrozole?

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on Jan 1, 2024.

Official answer

by Drugs.com

You can take letrozole (Femara) in the morning, midday or evening, but you should take it at about the same time each day. Taking it at the same time will help you to remember your dose. Letrozole is a tablet you take by mouth (with or without food), so you can take it with a meal if you prefer. If you miss a dose, do not double your dose the next day. Take your treatment exactly as prescribed by your doctor.

If letrozole causes you nausea, you can take your medicine at the same time each day with a small meal. Nausea is usually a temporary side effect that may subside in the first few days or weeks after you start treatment. If you have problems with nausea or vomiting, contact your doctor.

​​See a list of letrozole (Femara) side effects here in more detail.

Letrozole (Femara) is used to treat postmenopausal women to:

  • lower the risk of early-stage, hormone-receptor-positive breast cancer coming back after surgery and other treatments
  • lower the risk of early-stage, hormone-receptor-positive breast cancer coming back after 5 years of tamoxifen (Nolvadex, Soltamax)
  • treat advanced-stage, hormone-receptor-positive breast cancer, as first and second-line treatment

Aromatase inhibitors work by blocking the enzyme aromatase to help stop the production of estrogen, a female hormone, which can fuel breast cancer growth. This means that less estrogen is available to stimulate the growth of hormone-receptor-positive breast cancer cells.

There are 3 aromatase inhibitors available in the U.S. They are all approved as treatments for early, locally advanced or metastatic breast cancer.

  • anastrozole (Arimidex)
  • exemestane (Aromasin)
  • letrozole (Femara)

Learn more: What is the success rate for letrozole (Femara) in breast cancer?

This is not all the information you need to know about letrozole (Femara) for safe and effective use and does not take the place of your doctor’s directions. Review the full letrozole (Femara) information and discuss any questions you have with your doctor or other health care provider.

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References

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Letrozole is not chemotherapy, it is a type of hormone therapy that is used to treat people with breast cancer that is hormone receptor-positive. If your cancer is hormone receptor-negative, then letrozole will not be of any benefit. Traditional chemotherapy agents stop cancer cells from growing, dividing, and making more cells. Letrozole works by blocking the action of the enzyme aromatase, which prevents the body from converting androgens into estrogens. Estrogen is a hormone that causes estrogen receptor-positive (ER+) breast cancer to grow. Letrozole belongs to the class of medicines known as aromatase inhibitors. Continue reading

Although diabetes and blood sugar increases are not listed as a side effect of letrozole treatment, treatment with letrozole is associated with a significantly increased risk for high blood sugar levels and diabetes. An Israeli study that investigated 2,246 breast cancer survivors found that women treated with letrozole were 4.3 times more likely to develop diabetes than women not taking letrozole, although the number of women prescribed letrozole was small. Overall, women prescribed any sort of hormone treatment (either tamoxifen or an aromatase inhibitor such as letrozole) had a 2.5 times higher risk of diabetes. Continue reading

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