Letrazole chemical structure

This oral drug is in a class of medications called aromatase inhibitors, which was originally approved for treatment of advanced breast cancer. Doctors sometimes prescribe letrozole for women who don't ovulate on their own and who haven't responded to treatment with clomiphene citrate.

Preliminary studies have shown letrozole to be useful, especially for women whose uterine lining may be thinned out by clomiphene (Clomid). The usual dose of Femara® is 2.5mg. Side effects can include hot flashes, nausea, and vomiting. Letrozole is not approved by the FDA for inducing ovulation.

Letrozole works through the brain as well to cause release of FSH. Monthly pregnancy success rates with the use of Letrozole ovulation induction/ IUI is 5-12% per cycle. Multiple birth rates is approximately 10% with the majority of multiple pregnancies being twins.

Medication costs: 5 day course at 2.5 mgs/day; $40 to $60 depending on place of purchase. Letrozole is generally prescribed to be taken from days 3-7 of the menstrual cycle and has a short life span in the body.

There is some concern about the potential for birth defects if this medication is taken during pregnancy. In a medicated cycle, where it is given on days 3-7, there are no traces of the medication in the body by the time an embryo will be implanting. It is, however, important to rule out pregnancy before beginning this medication.

Side Effects

Side effects that you should report to your doctor or health care professional as soon as possible:

  • allergic reactions like skin rash, itching, or hives
  • bone fracture
  • chest pain
  • difficulty breathing or shortness of breath
  • severe pain, swelling, warmth in the leg
  • unusually weak or tired
  • vaginal bleeding

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):

  • bone, back, joint, or muscle pain
  • dizziness
  • fatigue
  • fluid retention
  • headache
  • hot flashes, night sweats
  • nausea

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