Understanding the association between hormone therapy and autoimmune disease risk

Autoimmune diseases disproportionately affect women, with notable shifts in incidence following menopause, suggesting a potential role of sex hormones in immune regulation.

A new study suggests a significantly higher incidence and risk of developing all autoimmune diseases (except Graves’ disease and autoimmune hepatitis) in postmenopausal women using hormone therapy.

Results of the study were presented at the 2025 Annual Meeting of The Menopause Society, held in Orlando, October 21–25.

Autoimmune diseases have been increasing globally for years and are expected to continue growing with women being the primary targets. Some studies have suggested that women might actually have a fourfold higher risk of being diagnosed with an autoimmune disease than men.

Researchers have already identified a number of factors related to the increase, including environmental factors and stress. There has been speculation that hormones influence immune responses, although the relationship with the development of autoimmune diseases in postmenopausal women remains poorly understood.

Hormone therapy continues to be the most commonly used and effective treatment for managing an array of bothersome menopause symptoms, including hot flashes.

A new large-scale study involving nearly 1.8 million women with a mean age of 60.5 years aimed to investigate the association between hormone therapy use and the incidence of autoimmune diseases among postmenopausal women. Compared to non-users, hormone therapy users had a higher incidence of autoimmune diseases at five years, 10 years, and across the full postmenopausal period.

When evaluating 17 individual autoimmune conditions over the full postmenopausal period, statistically significant increases in risk were observed for all autoimmune diseases except Graves’ disease and autoimmune hepatitis.

“Our study found a statistical link between hormone therapy and autoimmune diseases, but the actual increase in absolute risk is relatively small and varies by condition,” says Dr. Xuezhi (Daniel) Jiang, Professor of Obstetrics and Gynecology at Drexel University College of Medicine and lead author.

“Because this was a retrospective database study, more research is needed before drawing firm conclusions. Hormone therapy remains a safe and important option for many women when used appropriately but, like any treatment, it should be individualized while we await more research on its possible links to autoimmune disease.”

These findings highlight the need for further prospective research to verify these associations and to clarify potential underlying mechanisms and temporal relationships between hormone therapy use and autoimmune disease onset to support individualized risk-benefit evaluations in menopause care.

“Since more and more women are affected by autoimmune diseases, it’s important to consider all potential associations,” says Dr. Stephanie Faubion, medical director for The Menopause Society.

“That’s why we continue to recommend that health care professionals take a very individualized approach when prescribing hormone therapy. Although hormone therapy continues to be the first line therapy for managing menopause symptoms, it is not for everyone.”