By Dr. Courtney Holmes, APRN, The Alchemista
The Fear: “Will Hormones Give Me a Clot?”
If you’ve ever been told you have Factor V Leiden or a “clotting gene,” you’ve probably heard that hormone replacement therapy (HRT) is off-limits. The truth? That’s not entirely accurate anymore.
Modern research shows that the route of estrogen administration matters far more than we once thought. Oral pills and transdermal (skin-based) estradiol behave very differently inside the body — especially when it comes to blood-clotting risk.
The Science: Oral vs. Transdermal Estradiol
Over the last two decades, major clinical studies have transformed how we understand this relationship:
1️⃣ The ESTHER Study (Straczek et al., 2005)
In women carrying Factor V Leiden, oral estrogen significantly raised the risk of venous thromboembolism (VTE).
But women using transdermal 17β-estradiol (patch, gel, or spray) had no significant increase in clot risk compared with non-users.
👉 Read the study in Circulation
2️⃣ Follow-Up ESTHER Cohort (Canonico et al., 2007)
Confirmed that oral estrogen increases VTE risk, while transdermal estrogen does not — even when combined with progesterone.
👉 Read the study in Circulation
3️⃣ Review Article (Olié & Canonico, 2010)
Explains why: oral estrogen travels through the liver first, activating clotting proteins; transdermal estrogen bypasses the liver and avoids those changes.
👉 Read on PubMed
4️⃣ ACOG Committee Opinion (2013)
The American College of Obstetricians and Gynecologists recognizes that transdermal estrogen has little or no effect on clotting factors, unlike oral forms.
👉 ACOG Guidance
The Alchemista’s Bottom Line for Women with Factor V Leiden
If you carry Factor V Leiden, you are already predisposed to clot more easily, so caution makes sense.
But evidence consistently shows that:
Oral estrogen pills (like Premarin or oral estradiol) significantly increase clot risk in women with Factor V Leiden.
Transdermal estradiol (patches, gels, sprays) does not significantly increase that risk when properly dosed and monitored.
Progesterone choice matters too: natural micronized progesterone is neutral on clotting, unlike some synthetic progestins.
🕊 Reassurance: If you have Factor V Leiden, you don’t necessarily have to forgo hormone therapy.
When prescribed carefully, transdermal estradiol is the preferred, evidence-based option, even in carriers of Factor V Leiden, because it bypasses the liver and avoids the spike in clotting proteins that oral estrogen causes.
What This Means for You
At Milford Med Spa & Wellness, we always personalize hormone care.
Every plan begins with comprehensive history, lab testing, and discussion of genetics like Factor V Leiden.
If hormones are indicated, transdermal 17β-estradiol is our go-to route for safety and physiologic balance.
We pair it with progesterone when needed, regular monitoring, and lifestyle guidance for vascular health.
This is what alchemy in medicine looks like — turning science into empowerment, and evidence into ease.
The Takeaway
You deserve relief from menopause symptoms without fear.
For most women, including those with Factor V Leiden, transdermal estradiol offers a safe path to restore energy, mood, libido, and clarity while minimizing clot and stroke risk.
Your body isn’t broken, it’s evolving.
Let’s honor that transition with wisdom, safety, and grace.
With love & alchemy,
Dr. Courtney Holmes, APRN, The Alchemista
Milford Med Spa & Wellness
99 Cherry Street, Milford, CT
203-701-6161