QUESTION: Can women diagnosed with a progesterone-receptor-positive breast tumor use natural progesterone creams and supplements?
ANSWER: The safety of taking progesterone creams and supplements with or without progesterone receptors (but particularly with progesterone receptors present) is unknown. Sometimes even a little hormone can cause problems, including stimulation of breast tissue; whereas a higher dose may be even therapeutic. In other situations, it's the other way around. Very confusing! But until this whole hormone controversy is worked out, I'd err on the side of caution and avoid taking these supplements.
—Marisa Weiss, M.D.