Skip to main content

How do you take letrozole for fertility?

Medically reviewed by Sally Chao, MD. Last updated on July 30, 2021.

Official answer


Letrozole is a prescription medicine that may be used off-label to treat female infertility by inducing ovulation. Off-label use is when a provider prescribes a medication that has been studied and found to be safe and effective, but it is used for a different purpose than its approved use.

Letrozole is from a class of medications called aromatase inhibitors. It is approved by the U.S. Food and Drug Administration (FDA) for the treatment of certain types of breast cancer.

Letrozole Dosage for Infertility

The recommended starting dose of letrozole to induce ovulation is 2.5 mg once a day for 5 days, beginning between days 2 and 5 of menstrual bleeding. The medicine can be taken at any time during the day, but it should be taken at the same time each day. Food does not interfere with the medicine, so it can be taken before or after eating.

You are then monitored by various methods to determine if and when you are ovulating. Once ovulation occurs, your egg may be fertilized through timed sexual intercourse, intrauterine insemination or in vitro fertilization.

If pregnancy does not occur with the first cycle, the process may be repeated for more cycles and the letrozole dose may be increased by 2.5 mg increments up to 7.5 mg. How many cycles to try is a decision between you, your partner and your doctor.

Side effects

Because letrozole is used off-label in this situation, it is difficult to determine how common side effects are for this specific regimen. When letrozole is given to treat breast cancer (which may be for as long as five years), common side effects include:

  • Hot flashes
  • Muscle aches
  • Flushing
  • Headache
  • Dizziness
  • Bone pain
  1. American Society for Reproductive Medicine (ASRM). Medicines for Inducing Ovulation. 2016. Available at: [Accessed July 19, 2021].
  2. 2. Williams T, Mortada R, Porter S. Diagnosis and Treatment of Polycystic Ovary Syndrome.Am Fam Physician. 2016;94(2):106-113.
  3. U.S. Food and Drug Administration (FDA). Femara. April 2018. Available at: [Accessed July 15, 2021].
  4. U.S. Food and Drug Administration (FDA). Understanding Unapproved Use of Approved Drug "Off Label." Available at: [Accessed July 19, 2021].

Related medical questions

Drug information

Related support groups