Just found this:
"Modern scientific tests have shown that red clover contains isoflavones, plant based chemicals that produce estrogen like effects in the body. Isoflavones have shown potential in the treatment of a number of conditions associated with menopause, such as hot flashes, cardiovascular health, and osteoporosis. However, as researchers have become aware of the side effects of taking estrogen, there is also some concern about the safety of isoflavones. And the evidence that red clover helps reduce any menopausal symptoms -- like hot flashes -- is mixed."
"No serious side effects have been reported in people taking red clover for up to one year. General side effects may include headache, nausea, and rash. However, animals that graze on large amounts of red clover have become infertile.
People who have been diagnosed with breast cancer should not use red clover without discussing it with their physician."