For decades, hormone therapy has been used to treat symptoms of menopause like hot flashes, osteoporosis and vaginal dryness. Hormone therapy usually consists of doses of estrogen or progesterone either as a pill or applied to the skin as a patch, gel or spray. Different kinds of hormone therapies have been associated with risks such as increased chances of breast cancer, heart disease and blood clots if continued over long periods of time. Now scientists have found that it may also pose a higher risk of hearing loss.

Typically, hearing loss becomes common after menopause and it has long been assumed that hormone therapy will help prevent hearing loss among women. Previous studies have thrown up conflicting evidence of the effect of hormone therapy on hearing, with some suggesting harm and others suggesting benefits. Now, researchers at the Brigham and Women’s Hospital at Boston in the United States have examined the links between menopause, oral hormone therapy and self-reported hearing loss in 80,972 women in a long-term nurses health study conducted between 1991 and 2013.

They found that during the study period, 23% of the participants developed hearing loss but there was no significant association between menopause and risk of hearing loss. Women who underwent natural menopause at older ages were also at higher risk of hearing loss, although the mechanism of how this happens remains unclear. However, postmenopausal hormone therapy was associated with higher risk of hearing loss, and the risk tended to increase with longer use of hormones.

The researchers say that the findings, published in Menopause, the journal of The North American Menopause Society, are unexpected but significant for women who are evaluating the risks and benefits of undergoing hormone therapy.