Red Clover Side Effects and Warnings

Safety Issues

Red clover is on the Food and Drug Adminstration's Generally Recognized as Safe (GRAS) list and is included in many beverage teas. However, detailed safety studies have not been performed.

Because of its blood-thinning and estrogen-like constituents, red clover should not be used by pregnant or nursing women, or women who have had breast or uterine cancer. A study investigating the safety of red clover in women with a family history of breast cancer found no changes in breast density or thickness of the uterine lining over a three-year period, which is somewhat reassuring. ¹ However, the study was much too short to determine red clover's long-term effect on cancer risk. Safety in young children or those with severe liver or kidney disease has also not been established.

Based on their constituents, red clover extracts may conceivably interfere with hormone treatments and anticoagulant drugs (see the next section for specific drugs).

One double-blind study of post-menopausal women found the use of red clover isoflavones at a dose of 80 mg daily for 90 days resulted in increased levels of testosterone. ² The potential significance of this is unclear. The same study found that red clover isoflavones reduced the thickness of the uterine lining, a finding that suggests low possibility for endometrial cancer.

For other potential risks due to the isoflavones in red clover (especially in concentrated isoflavone-rich extracts of red clover), see the full article on Isoflavones .

Interactions You Should Know About

• If you are taking hormones or blood-thinning drugs—such as warfarin (Coumadin) , heparin , clopidogrel (Plavix), ticlopidine (Ticlid), pentoxifylline (Trental) , or even aspirin : Red clover should be used only under a physician's supervision.