A large Danish study has found that the pill form of menopause hormone therapy is linked to a higher risk of blood clots in the legs or lungs.
Using a skin patch or gel, the study found, does not carry the same risk.
The nested case-control study, published in The BMJ, tracked women aged 50 to 69 in Denmark between 2003 and 2021.
Researchers compared nearly 10,000 women who developed a blood clot in a vein against roughly 49,000 who did not.
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Current use of oral menopausal hormone therapy was tied to an increased risk of venous thromboembolism.
That is the medical name for a clot in a deep vein that can travel to the lungs.
The absolute increase was 0.09 percent per year for clots. That works out to about 1 extra case per 1,055 women taking the pill each year.
The higher risk showed up regardless of dose or how long a woman had been on treatment.
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Stroke and heart attack risks were tied only to high-dose oral estradiol above 1 milligram per day taken for more than a year.
In those women, the numbers worked out to 1 extra stroke per 1,642 users a year and 1 extra heart attack per 3,846, writes News-Medical.
Where the pill and the patch part ways
Transdermal therapy is delivered through the skin as a patch, gel or spray.
It showed no general increase in thrombotic risk regardless of regimen, dose or duration, the authors reported.
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The route matters because pills pass through the liver first.
There, they push up production of the clotting proteins that make blood stickier.
Patches and gels bypass the liver and deliver estrogen directly into the bloodstream.
Why this matters for millions of women
The distinction is anything but abstract in the United States.
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Estrogen-based hormone therapy prescribing has more than doubled since 2018, according to prescription data from Truveta.
By February 2026, about 1 in 20 women aged 45 to 54 had an active estrogen-based prescription.
Patch dispensing has grown faster than pills over that period, but oral estrogen is still widely prescribed.
Warning signs of a blood clot
A clot in a leg vein does not always announce itself.
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About half of people with a deep vein thrombosis feel nothing at all, the CDC notes.
When symptoms do appear in a leg, they include swelling, pain or tenderness, warmth, and redness or discoloration. Usually only one leg is affected.
A clot that breaks loose and travels to the lungs is called a pulmonary embolism.
Sudden shortness of breath, a fast or irregular heartbeat, chest pain that worsens with a deep breath, coughing up blood, or lightheadedness and fainting are the warning signs.
Those symptoms need emergency care.
Talk to your doctor before changing anything
For most women, the absolute clot risk from oral hormone therapy remains low.
But the study strengthens the case for considering a patch or gel first when starting treatment.
Women already on oral therapy should not simply stop.
Abrupt withdrawal can bring hot flashes, night sweats and other menopause symptoms roaring back.
The practical step is to ask a prescriber whether switching to a patch or gel makes sense for you.
This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.