Red clover may interfere with the body's ability to process some drugs that are broken down by liver enzymes. For that reason, you should check with your doctor before taking red clover.

Estrogens, hormone replacement therapy, birth control pills -- Red clover may alter the effects of any drugs containing hormones or derivatives of hormones, as well as the levels of hormones in the body.

Tamoxifen -- Red clover may interfere with tamoxifen.

Anticoagulants (blood thinners) -- Red clover may enhance the effect of these drugs, as well as herbs and supplements that have blood-thinning effects (such as ginkgo, ginger, garlic, and vitamin E).

Diabetes drugs -- Red clover may lower blood sugar and alter the effects of drugs taken to control diabetes.