09/27/2026
If you take estrogen, are considering it, or have been afraid to take it because of what you’ve heard about the risks, this new study is worth reading.
A large new study published this week in The BMJ looked at the risks associated with menopausal estrogen therapy. But importantly, the researchers didn’t just ask whether women were taking estrogen. They looked at which estrogen they were taking, the dose, how they were taking it, and how long they had been taking it.
And that distinction is important, because estrogen is not one medication.
There is estradiol, which is bioidentical to the estrogen your ovaries naturally produce. There are also other forms of estrogen, including conjugated estrogens and synthetic estrogens such as ethinyl estradiol.
And then there is how you take it.
A pill.
A patch.
A gel or spray.
A vaginal cream, tablet, insert, or ring.
Different estrogen. Different dose. Different route.
And those differences can matter when we talk about risk.
Researchers used Denmark’s national health records to look at women ages 50–69 over an 18-year period. They looked at the specific hormones women were prescribed, the dose, how they took them, how long they used them, and whether they developed a DVT or pulmonary embolism, ischemic stroke, or heart attack.
Women taking oral estrogen had about a 60% higher relative risk of DVT or pulmonary embolism.
But if you take oral estrogen, don’t panic when you see that 60%.
The absolute risk was still small.
Among women not using hormone therapy, there were about 16 blood clots per 10,000 women per year.
With oral estrogen, that increased to about 25 per 10,000 women per year.
So a 60% increase in relative risk sounds pretty dramatic. In absolute numbers, it was approximately 9 additional blood clots for every 10,000 women treated for a year.
Both numbers are true. Both are important when we’re deciding what a risk actually means for an individual woman.
Transdermal estradiol was different.
Women using estradiol through the skin, with a patch, gel, or spray, did not have an overall increased risk of blood clots.
For stroke and heart attack, the increased risk associated with oral estradiol was concentrated in women taking doses greater than 1 mg per day for longer than a year.
There is an important limitation to all of this.
This was an observational study, not a randomized clinical trial.
In an observational study, researchers don’t decide which treatment someone receives. They look at what is already happening in the real world. In this case, they looked at which estrogen women had been prescribed and what happened to them afterward.
In a randomized clinical trial, researchers would randomly assign women to different treatments and then follow them to see what happened. Randomization helps make the groups more similar from the beginning, which gives us more confidence that differences in outcomes are actually related to the treatment.
That matters because women prescribed oral estrogen may have been different in other ways from women prescribed patches or women who weren’t taking estrogen at all.
Researchers can adjust statistically for many of those differences, but they can’t account for everything. This study, for example, did not have information about two pretty important risk factors: smoking and BMI.
So we can say that oral estrogen was associated with more blood clots.
We cannot say from this study that oral estrogen caused those blood clots.
That doesn’t make the findings unimportant. Large observational studies give us valuable information about what happens to people in the real world, particularly when we’re looking at relatively uncommon events.
And if you take oral estrogen, this study is not a reason to panic or suddenly stop taking it.
The absolute risk was small.
Oral estrogen is not automatically a bad choice, and a patch is not automatically the right choice for every woman.
But this study is another reason I think we need to stop asking:
“Is estrogen safe?”
The better questions are:
Which estrogen?
What dose?
Taken how?
For how long?
And in whom?