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Breast enlargement pills contain a proprietary blend of ingredients that are specific to the manufacturer. With each ingredient comes the potential for side effects. According to Mayo Clinic, breast enlargement may also be an unintended side effect of certain prescription drugs like estrogen, birth control pills and antidepressants. They also point out that no published studies have shown that natural breast enhancement supplements have shown the same results. Review the ingredients in any breast enlargement pills that you intend to take and identify their individual side effects. Mayo Clinic suggests talking to your doctor for more effective options for breast enhancement.

Breast Cancer

Mayo Clinic identifies one common ingredient in breast enlargement supplements as phytoestrogens, a herb that could increase the risk for some types of breast cancer. Cancerhelp.org.uk also supports the notion that dense breast tissue is a definite factor in elevating the risk of cancer. They suggest that phytoestrogens and other hormones have shown to both increase and decrease the risk of cancer in different individuals.

Changes in Blood Composition

Several potential ingredients in breast enlargement pills may change the composition of the blood. Compounds like Pueraria mirifica and saw palmetto are known to cause anemia or slow the clotting of blood. These side effects can be especially dangerous for individuals already suffering from other health issues such as high blood pressure. Taking prescription blood-thinning medication, like warfarin, and breast enlargement pills concurrently may lead to a serious drug interaction if clotting is slowed.

Other Side Effects

Breast enlargement pills containing any form of estrogen or synthetic estrogens can be harmful for infants of pregnant or breastfeeding women. The inclusion of bovine ovary extract can also lead to the formation of milk in the breasts and a rise in prolactin hormone levels. Effects of taking this may include irregular menstruation, infertility, increased risk of stroke and a reduced libido.