Health Risks of Menopausal Hormone Replacement Therapy (HRT)

What is menopausal hormone replacement therapy?

Menopausal hormone replacement therapy is the use of medications made up of estrogen alone or estrogen plus progestin to manage the side effects of menopause. Progestin is a synthetic hormone that works like progesterone. These hormone replacements come from plants, animals, or are made in a laboratory. Hormone replacement therapy (HRT) was commonly prescribed to reduce hot flashes, vaginal dryness, the risk of bone fractures, and heart disease.

History of HRT

In July 2002, a large study found that HRT was doing more harm than good and changed healthcare providers' practice. The Women's Health Initiative (WHI) found that taking HRT (estrogen combined with progestin) increased the risk of breast cancer, heart disease, stroke, and blood clots. While there was the benefit of reduction in bone fractures related to osteoporosis and fewer colorectal cancer cases, the risks far outweighed these benefits. Around the same time, the HERS study found that taking HRT resulted in no decrease in heart attacks in older women with heart disease. A few years later, the WHI study also found that taking estrogen alone (for women without a uterus) resulted in an increased risk for stroke and blood clots and no improvement in heart disease.

A follow-up study confirmed that women who take HRT for longer than 5 years, double their annual risk of breast cancer. The study did find that after stopping HRT, the risk decreases significantly. The WHI is continuing to follow the participants to determine any long-term risks related to HRT.

How is HRT used now?

Healthcare providers now recommend that women take HRT only when absolutely necessary to control menopausal symptoms in the lowest possible doses, for the shortest time possible. The WHI is continuing to follow the participants to determine any long-term risks related to HRT.

What can you do if you took HRT in the past? Be sure your healthcare providers know that you took HRT, and for how long. You can periodically check on the WHI website to learn about study updates.

Learn more from Dr. Susan Love Research Foundation and the National Institutes of Health.