Dr. Robert D. Frisina, from the University of Rochester Medical Center in Rochester, N.Y. conducted a small study in which she wanted to investigate previously associated HRT and hearing loss. A study included 124 postmenopausal women and found that only combined HRT that included both estrogen and progesterone had such effect on postmenopausal women. However, women who didn’t use HRT or those who used estrogen alone had no problems understanding speech of other people.

Progesterone is often added to hormone replacement therapy in order to lessen the effects of excessive estrogen on the female body that has been previously used alone in HRT and linked to breast, cervical and endometrial cancer.

Hearing problems related to the presence of progesterone in HRT affect the inner ear and some brain functions that affect hearing.
Dr. Robert D. Frisina who led the study warns women to have frequent hearing tests if undergoing combined HRT and urges doctors as well as manufacturers to include hearing problems into possible side effects and acknowledge the women about them, so that they could make a more informed decision about their treatments.