Are menopause hormone patches safer than pills for clots?
Yes, in this large Danish study. Menopause hormone therapy taken as a pill raised the risk of blood clots in the legs or lungs, while patches and gels through the skin did not raise overall clot risk. The extra risk from pills was small in absolute terms: about 1 additional clot for every 1,055 women treated for a year.
Blood clots are the main safety worry with menopause hormone therapy. A clot can form in a leg vein and travel to the lungs, which doctors call venous thromboembolism. Clots in arteries can cause strokes and heart attacks. This study asked whether today’s hormone therapy raises any of those three risks, and whether it matters if the hormone is swallowed or absorbed through the skin. The answer is that the route matters a lot.
What the data show
Start with the baseline. Among women who had not used hormone therapy, there were 15.8 leg or lung clots, 20.3 strokes caused by a blocked artery, and 13.0 heart attacks per 10,000 women each year.
Compared with women not currently on hormones, women taking oral estrogen (alone or with a progestin) had about 60% higher risk of a leg or lung clot (hazard ratio 1.6). The true increase is very likely between 50% and 80%. In absolute terms, that is 0.09% per year, or about 9 extra clots for every 10,000 women per year. Put another way, 1,055 women would need to take hormone pills for a year for one extra clot to occur.
Pills also carried about 30% higher stroke risk (hazard ratio 1.3) and about 20% higher heart attack risk (hazard ratio 1.2). Those translate to about 6 extra strokes and 3 extra heart attacks per 10,000 women per year. That means one extra stroke for every 1,642 women and one extra heart attack for every 3,846 women on pills for a year.
The clot risk with oral estradiol showed up at every dose and every length of use. The strongest stroke and heart attack signal came with high doses. Oral estradiol above 1 mg a day, taken for more than a year, was linked to more strokes and heart attacks, and the risk grew with time. After more than 5 years, stroke risk was about 80% higher (hazard ratio 1.8, very likely between 40% and 120% higher), and heart attack risk was also about 80% higher (hazard ratio 1.8, very likely between 40% and 140% higher).
Dr. Kumar’s Take
This study gives a practical answer to a question every woman considering hormone therapy should ask: pill or patch? For leg and lung clots, the pill carried a consistent extra risk and the skin route did not. That is a meaningful difference, and it is a choice women can discuss with their doctor.
The absolute numbers matter just as much. One extra clot per 1,055 women a year is a real risk, but it is a small one. For a woman with severe hot flashes or poor sleep, that trade may be well worth it. The relative figure of “60% higher” sounds alarming on its own, which is why the absolute number belongs next to it.
There is one exception worth knowing. Transdermal combined cyclic therapy, where a progestin is added in cycles to an estrogen patch or gel, was linked to about double the heart attack risk (hazard ratio 2.1). The range was wide, very likely between 10% and 310% higher, so this estimate is shaky. It still deserves follow-up in future studies.
How the study was done
Researchers used Denmark’s national health registries to follow women aged 50 to 69 living in Denmark between 2003 and 2021. They identified 9,807 women with a leg or lung clot, 18,460 with a stroke from a blocked artery, and 11,974 with a heart attack. Each group was matched by birth year to women without these conditions: 49,035, 92,300, and 59,870 women, respectively. The researchers then compared hormone use between the two groups.
Women with a history of clots, cancer, liver disease, inherited clotting disorders, ovary removal, fertility treatment, endometriosis, or polycystic ovary syndrome were excluded. That keeps the comparison cleaner, but it also means the results apply to relatively healthy women.
This is an observational design. It shows a link, not proof that the hormones caused the clots. Women who choose pills may differ from those who choose patches in ways the registries cannot fully capture.
Practical Takeaways
- If you are considering menopause hormone therapy and blood clots are a concern, ask your doctor about a patch or gel, since the skin route did not raise overall clot risk in this study.
- If you already take hormone pills, do not stop suddenly on your own; bring this study to your doctor and discuss whether switching routes makes sense for you.
- If you take oral estradiol above 1 mg a day, ask whether a lower dose could work, since the stroke and heart attack signal was tied to high doses used for more than a year.
- Keep the absolute numbers in view: about 1 extra clot per 1,055 women per year on pills is a small risk that has to be weighed against how much your symptoms affect your life.
Related Studies and Research
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FAQs
Does estrogen gel cause blood clots?
In this Danish study, estrogen absorbed through the skin by patch or gel was not linked to a higher overall risk of leg or lung clots, strokes, or heart attacks compared with no current hormone use. The one exception was a higher heart attack estimate with combined cyclic therapy through the skin, and that estimate was imprecise. Gel and patch users should still report leg swelling, chest pain, or sudden shortness of breath right away, as anyone should.
Is a low dose of oral estrogen safe for blood clots?
Not fully, based on these findings. The researchers found that oral estradiol raised leg and lung clot risk regardless of dose or how long it was taken. The clearest added stroke and heart attack risk was tied to doses above 1 mg a day used for more than a year. So a lower oral dose still carries the clot risk seen with every oral dose.
How long can you safely take menopause hormone pills?
For leg and lung clots, the extra risk from pills appeared at every length of use, so it does not seem to build up only after years. For strokes and heart attacks, length of use mattered with high-dose oral estradiol, where risk rose the longer women took it and reached about 80% higher after more than 5 years. That makes periodic review of dose and route with a doctor sensible for anyone on long-term oral therapy.
Bottom Line
Among Danish women aged 50 to 69, menopause hormone pills raised the risk of leg and lung clots by about 60%, which works out to 1 extra clot for every 1,055 women treated per year. Patches and gels did not raise overall clot risk. High-dose oral estradiol taken for years was also linked to more strokes and heart attacks. For women who want hormone therapy but worry about clots, the route of delivery is one of the most useful choices on the table.
