Does natural progesterone have any side effects?
Progesterone binds with progesterone receptor sites in the brain and causes a calming effect on the central nervous system. In excessive amounts, progesterone may have a relaxing effect on the brain, and may cause drowsiness. In a very small group of women who are extremely sensitive, progesterone of any kind may aggravate hormonal headaches or PMS symptoms. There are no long-term adverse effects noted for supplemental progesterone in amounts that replicate physiological levels of progesterone in the body.
