Tamoxifen is a medication known as a selective estrogen receptor modulator or SERM. Tamoxifen is the oldest drug approved by the U.S. Food and Drug Administration to treat breast cancer. Some women who have a family history of the disease and a high risk of developing breast cancer may use the medication as a preventive measure. SERM drugs do not allow estrogen to bind to the proteins found in breast tissue. Tamoxifen can reduce the risk of breast cancer and osteoporosis in some people, but it has negative side effects associated with it as well. Minor side effects include hot flashes, nausea, headaches and irregular menstruation. The medicine can also increase the risk of serious medical conditions that may be seen as permanent side effects.
Stroke
A permanent side effect that is a possibility when taking tamoxifen is stroke. As explained by both the National Cancer Institute and BreastCancer.org, taking tamoxifen can increase a person's risk of developing blood clots, which can lead to a heightened risk of stroke. Effects of a stroke vary from person to person and can be fatal in some cases. Paralysis and loss of verbal communication can be permanent after effects of a stroke.
Uterine Cancer
The nature in which tamoxifen acts on estrogen can leave a women more susceptible to uterine and endometrial cancers, according to the National Cancer Institute. The percentage of women affected by uterine sarcoma or endometrial cancer increases by a percentage point from 1 to 2 percent if she is currently taking tamoxifen to treat or reduce the risk of breast cancer. Women who do develop these life-threatening cancers as a result of the medication face a host of health issues that may become permanent, including infertility and organ damage that can be caused by chemotherapy.
Cataracts
The National Cancer Institute states that women who take tamoxifen have a higher risk of developing cataracts. A cataract is a clouded area of the lens of the eye. Cataracts can be treated, removed and thus are not necessarily permanent, but the effects of the eye disease can be a lifelong condition. Some people who have cataract correction surgery may not regain all the vision lost and could become classified as having low vision permanently.
Stunted Growth
Studies performed on rats and reported in the May 2007 issue of the scholarly journal "Bone" suggest that tamoxifen could retard growth if taken by people who have not yet reached their full height potential. Researchers at the Karolinska Institutet in Stockholm, Sweden, explain that high levels of estrogen are sometimes prescribed to limit growth in girls who are on track to becoming extremely tall and that tamoxifen may be tried to achieve the same result. On the other side of the issue, stunted growth could potentially become a permanent side effect for people who take tamoxifen to treat breast cancer or gynecomastia and who are not trying to limit their height.
