Hormone Therapy for Hot Flashes and Your Heart: What a New 20-Year Study Shows

Written By Dr. Mark L. Meyer

Vannoni 2026

Few questions come up in my Midtown office as often as this one, usually from a woman in her late 40s or early 50s who has been waking up drenched at 3 a.m. for months: "Is hormone therapy safe for my heart?"

A large new study published in JAMA Internal Medicine adds an important piece to the picture, and I want to walk you through what it found, what it does not prove, and how to use it in a conversation with your own doctors.

Why Has Hormone Therapy Become So Confusing?

In 2002, the Women's Health Initiative (WHI) trial made headlines when it reported more heart attacks, strokes, and blood clots in women taking hormones. Prescriptions dropped almost overnight.

What got lost in the headlines was who was in that trial. The average participant was in her early 60s, and many were well past menopause when they started taking hormones.

In the years since, researchers have looked much more closely at age and timing. In November 2025, the FDA announced it was removing the "black box" warnings from most menopausal hormone therapy products and adding language noting that women may benefit when therapy is started within 10 years of menopause.

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What Has The New Study Found?

The new research comes from the Study of Women's Health Across the Nation, known as SWAN, which followed a diverse group of American women through midlife from 1997 to 2017. Investigators from the University of Pittsburgh, Virginia Commonwealth University, and other centers focused on 2,737 women who had hot flashes or night sweats, had no history of heart disease, and had never used hormone therapy.

They used a method called "target trial emulation." In plain terms, the researchers took long-term observational data and organized it to mimic a clinical trial as closely as possible, comparing women who started hormone therapy with similar women who did not.

Here is what they found:

  • Women who started menopausal hormone therapy had a 22% lower risk of cardiovascular events, including heart attack, stroke, heart failure, procedures to reopen blocked arteries, and related deaths.

  • Women who started within 10 years of menopause had an estimated 27% lower risk.

  • Women who started more than 10 years after menopause saw no benefit. The estimate actually leaned toward higher risk, though the numbers in that group were too small to be certain.

What Is The Timing Hypothesis, in Plain English?

Cardiologists and gynecologists often talk about a "window of opportunity." One leading explanation is that estrogen seems to help blood vessels that are still relatively healthy. In women who are many years past menopause, arteries may already contain plaque, and adding hormones at that stage may not help and could potentially cause harm.

A 2025 reanalysis of the original WHI trials, also published in JAMA Internal Medicine, points in the same direction. Among women with moderate to severe hot flashes, hormone therapy did not raise cardiovascular risk in those aged 50 to 59, while risk rose clearly in women 70 and older. Two very different kinds of studies are telling a similar story.

Are There Differences by Race?

One of the more striking findings involved Black women, who showed the strongest association, with roughly half the risk of cardiovascular events after starting hormone therapy. Black women in SWAN also tend to experience more frequent and more severe hot flashes. Estimates for other racial and ethnic groups were less precise, so we should be careful about drawing firm conclusions there.

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Why Do Cardiologists Care About Hot Flashes?

Hot flashes are not just an annoyance. Research from SWAN and related studies has linked frequent or persistent hot flashes with higher blood pressure, less favorable cholesterol, and early signs of artery changes. When a patient tells me she is having severe symptoms, I take it as a cue to look more closely at her overall heart risk, not only at her comfort.

What This Study Does Not Say?

I want to be clear about the limits here. This was not a randomized trial. Women who choose hormone therapy may differ from those who do not, for example in income, access to care, or general health. The researchers tried to account for this, but they cannot rule it out entirely.

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What Some Practical Steps Women in New York Can Take?

If you are in your 40s or 50s and struggling with hot flashes, here is how I suggest approaching it:

  1. Know when your menopause started. Timing is central to this decision, so jot down when your last regular period was.

  2. Get a full heart risk check. Blood pressure, cholesterol, blood sugar, and family history should all be on the table before you start or skip therapy.

  3. Talk to your gynecologist and cardiologist together. The best decisions happen when both specialists see the whole picture.

  4. Ask about the type and dose. Pills, patches, and gels are not identical, and your doctor can help match the option to your risk profile.

  5. Keep up the basics. Therapy does not replace daily movement. Taking the stairs at your subway station, walking the Hudson River Greenway, or getting off the bus a stop early all add up.

For healthy women in their 40s and 50s who are dealing with hot flashes and night sweats, this new study offers reassurance: starting hormone therapy within about 10 years of menopause was linked to lower, not higher, cardiovascular risk. Starting much later did not show the same benefit. The study cannot prove cause and effect, and hormone therapy is still a personal decision that depends on your full health history. If you are weighing it, bring your questions to your doctors, get your heart numbers checked, and make the choice with the complete picture in front of you.

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Sources

  1. Robertson S. Menopausal Hormone Therapy May Have Heart Benefits for Some Women With Vasomotor Symptoms. MedPage Today. September 2026. https://www.medpagetoday.com/obgyn/menopause/122921

  2. Wang Z, et al. Menopausal Hormone Therapy and Cardiovascular Risk in Midlife Women With Vasomotor Symptoms. JAMA Internal Medicine. 2026. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2853611

  3. Menopausal Hormone Therapy and Cardiovascular: Laying the Foundation for Future Trials (Invited Commentary). JAMA Internal Medicine. 2026. https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2853616

  4. Starting Hormone Therapy Within 10 Years of Menopause Was Linked to Lower Heart Risk in a 20-Year Analysis. Medical Daily. 2026. https://www.medicaldaily.com/menopause-hormone-therapy-heart-risk-timing-swan-jama-study-478516

  5. Menopausal Hormone Therapy and Cardiovascular Diseases in Women With Vasomotor Symptoms: A Secondary Analysis of the Women's Health Initiative Randomized Clinical Trials. JAMA Internal Medicine. 2025. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2838720

  6. Hormone Therapy Does Not Increase Cardiovascular Disease Risk in Younger Postmenopausal Women. Northwestern Medicine Feinberg School of Medicine News. December 2025. https://news.feinberg.northwestern.edu/2025/12/05/hormone-therapy-does-not-increase-cardiovascular-disease-risk-in-younger-postmenopausal-women/

  7. U.S. Food and Drug Administration. HHS Advances Women's Health, Removes Misleading FDA Warnings on Hormone Replacement Therapy. November 2025. https://www.fda.gov/news-events/press-announcements/hhs-advances-womens-health-removes-misleading-fda-warnings-hormone-replacement-therapy

  8. FDA Removes Menopause Hormone Therapy Black Box Warnings. Harvard Health Publishing. https://www.health.harvard.edu/womens-health/fda-removes-menopause-hormone-therapy-black-box-warnings

  9. Thurston RC, et al. Vasomotor Symptoms and Cardiovascular Health: Findings From the SWAN and the MsHeart/MsBrain Studies. Climacteric. 2024. https://pubmed.ncbi.nlm.nih.gov/37577812/

  10. El Khoudary SR, et al. Menopause Transition and Cardiovascular Disease Risk: Implications for Timing of Early Prevention. A Scientific Statement From the American Heart Association. Circulation. 2020. https://www.ahajournals.org/doi/10.1161/CIR.0000000000000912

Dr. Mark L. Meyer

Dr. Meyer graduated from Haverford College with a Bachelor of Science, High Honors, in cellular and molecular biology, Phi Beta Kappa, Magna Cum Laude. He attended the Yale University School of Medicine, where he also completed a categorical residency in Internal Medicine, served for one year as an Emergency Department attending physician, and held the title of Clinical Instructor in the Department of Surgery. During this time, Dr. Meyer obtained a J.D. from the Yale Law School, concentrating on medical ethics, scientific research law, and FDA law. He then completed a fellowship in Cardiovascular Diseases at the Hospital of the University of Pennsylvania, where he obtained Level 3 Nuclear Cardiology training.

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