Femara Side Effects for Fertility
Femara is a medication that helps induce ovulation in women who do not ovulate on their own. It also causes stronger ovulation, or super-ovulation, in women who do ovulate but have had difficulty achieving pregnancy. Some reproductive specialists prefer Femara over more traditional medications because it does not negatively affect the uterine lining. Femara was originally developed as a treatment for breast cancer, and does carry the risk of side effects.
Low Estrogen Levels
Dr. Randy S. Morris, fertility specialist and associate clinical professor at the University of Illinois School of Medicine, explains that Femara decreases estrogen levels in a woman’s body. For infertility, Femara is only prescribed for five days at the beginning of a woman’s cycle; for this reason, side effects related to decreased estrogen are few. Still, some women experience hot flashes, headaches and breast tenderness when taking this medication.
Possible Birth Defects
The Advanced Fertility Center of Chicago explains that the half life, or time it takes the medication to clear the blood stream, is so short when taken as directed, that it shouldn’t be in the body by the time egg fertilization occurs 2. This decreases the chance of adverse effects on the embryo. If a woman were to unknowingly be pregnant at the time Femara was taken, however, birth defects could occur. For this reason, many fertility clinics perform both a pregnancy test and an ultrasound prior to allowing a patient to begin taking Femara.
Femara is a medication that causes ovulation, and therefore carries the risk of causing more than one egg to be released at a time. Georgia Reproductive Specialists notes that women who take Femara to achieve pregnancy have as much as a 10 percent chance of having twins. Triplets and quadruplets are far rarer at one in 400 births and one in 800 births respectively.
Due to the ovarian stimulation caused by taking Femara, it is possible even though it’s rare, for a woman to develop ovarian cysts after taking the medication. An ovarian cyst is a buildup of fluid inside the ovary and may occur when one or more eggs mature but fails to release into the fallopian tubes. Cysts are more common with other fertility treatments, though they are still a possibility with Femara. They will usually resolve without treatment. (Reference 3)
Other Side Effects
Other less serious side effects that have occurred with the use of Femara include stomach and intestinal upset, dizziness, sweating, swelling, difficulty sleeping, abdominal pain, allergic reactions and chest pain. All side effects should be discussed with a physician or other medical provider.
- Dr. Randy S. Morris/IVF1.com: Femara for Infertility Treatment
- Advanced Fertility Center of Chicago: Femara for Infertility
- Drugs.com: Femara
- U.S. Food and Drug Administration. Highlights of Prescribing Information: Femara (letrozole) for oral use. Silver Spring, Maryland; updated July 2017.
- Lafourcade, A., His, M., Baglietto, L. et al. Factors associated with breast cancer recurrences or mortality and dynamic prediction of death using history of cancer recurrences: the French E3N cohort.BMC Cancer. 2018;18:171. DOI: 10.1186/s12885-018-4076-4.
- Dhesy-Thind, S.; Fletcher, C.; Blanchette, P. et at. Use of Adjuvant Bisphosphonates and Other Bone-Modifying Agents in Breast Cancer: A Cancer Care Ontario and American Society of Clinical Oncology Clinical Practice Guideline.J Clinical Oncol. 2017;35(18):2062-81. DOI: 10.1200/JCO.2016.70.7257.
- Hague, R.; Shi, J.; Schottinger, J. et al. Cardiovascular Disease After Aromatase Inhibitor Use. JAMA Oncol. 2016;2(12):1590. DOI: 10.1001/jamaoncol.2016.0429.
- Goss, P.; Ingle, J.; Pritchard, K. et al. Extending Aromatase-Inhibitor Adjuvant Therapy to 10 Years. N Eng J Med. 2016 Jun;375(3):209-19. DOI: 10.1056/NEJMoa1604700.
- Henry, N.; Azzouz, F.; Desta, A. et al. Predictors of Aromatase Inhibitor Discontinuation as a Result of Treatment-Emergent Symptoms in Early-Stage Breast Cancer. J Clin Oncol. 2012;30(9):936-42. DOI: 10.1200/jco.2011.38.0261.
- Senkus, E.; Kyriakides, S.; Ohno, S. et al. Primary breast cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2015;26 (suppl 5):v8-v30. DOI: 10.1093/annonc/mdv298.
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