The widespread and common use of natural progesterone (hereafter referred to as progesterone) for hormone balance and menopausal symptoms, especially estrogen dominance, has potentially important negative clinical implications when used by those with a weak body – such as those with Adrenal Fatigue Syndrome (AFS). Source : https://www.drlam.com/blog/serious-progesterone-side-effects-and-brittle-adrenals-part-1/30858/