Side Effects of Tamoxifen

Tamoxifen (brand name Nolvadex) is a drug that the doctors have been prescribing for over a quarter of a century to fight breast cancer. It is a pill that is taken orally and it works against breast cancer by competing with the female hormone estrogen in the body. It is also useful for preventing breast cancer in women. For those in an early stage of the disease, tamoxifen is used as an additional treatment. It has also been found effective in preventing the spread of cancer from one breast to the other. However, like most other drugs, there are certain side effects of tamoxifen that raises health concerns among the users of this drug.

How Does Tamoxifen Work

Cancer refers to the uncontrolled division of cells. Some breast cancers are referred to as estrogen receptor positive. This means that they require estrogen to grow. Tamoxifen acts as an anti-estrogen by competing with the hormone to bind with the estrogen receptor sites in the breast cancer cells. By binding to these sites, tamoxifen slows the growth and division of the cancerous cells in the tissue. Hence, Tamoxifen is often called an 'anti-estrogen' or 'Selective Estrogen Receptive Modulator' (SERM). Breast cancer research has shown that tamoxifen is effective in treating only estrogen receptor positive breast cancers. Therefore before it is used as a treatment option for breast cancer, the tumor's hormone receptor status should be determined. Although tamoxifen acts as an anti-estrogen in the breast tissue, it acts like the hormone in other tissues. It is due to this reason that women may derive the benefits of menopausal estrogen replacement therapy which may include reduced risk of osteoporosis.

Tamoxifen Side Effects

Although effective in breast cancer treatment, tamoxifen has a number of side effects. Some of them are:

• Tamoxifen causes menopausal symptoms in almost 50% of the women who take this medicine. The most common symptoms are hot flushes and irregular periods. This is most common in women who haven't yet had menopause but are nearing the stage. However, such symptoms may not be exclusively due to the drug.
• Uncomfortable side effects like vaginal discharge may be caused in some women that may become difficult to cope with. This might make one feel uncomfortable and reduce the urge for intercourse.
• One must not try to conceive while using the drug as it may cause certain birth defects in the child. If one is planning to start a family, one should consider it only months after the woman has stopped taking tamoxifen.
• Developing blood clots (deep vein thrombosis) is a possible side effect of tamoxifen. 1 in every 100 women is at risk of developing deep vein thrombosis that refers to a blood clot being formed in a large vein, usually in that of the leg. Women who cannot move around freely, like those recovering from a surgery are a greater risk of developing such kinds of blood clots. If the clot travels through the blood up to the lungs, it may result in severe consequences.
• Tamoxifen may slightly increase the risk of developing cancer in the lining of the womb of the women who use this drug. In medical terms it is referred to as endometrial cancer. However, very few women are at a risk of developing this type of cancer.
• For women who haven't yet reached menopause, tamoxifen may reduce the density of the bones. However, in women who have reached menopause, tamoxifen acts to strengthen the bones.
• Other side effects include fatigue, difficulty in breathing, nausea and weight loss.
• Some also have allergic reactions that may manifest as itching, skin rash, swelling and hives.

Despite its harmful side effects, tamoxifen has proved beneficial for women who have already reached menopause. Besides increasing the bone density, this drug helps in lowering the levels of cholesterol in such women. Some studies have shown that women who have taken this drug for 5 years after they underwent surgery for early breast cancer were at a lesser risk of dying of heart disease in the next 10 years than those who took the medicine for just two years.

Despite all the various side effects of tamoxifen, doctors recommend this drug for its efficacy in treating and preventing breast cancer. The side effects may vary among different women. However, in case any of the side effects become severe, it is best to consult one's physician without any delay.