top of page
Search

Estrogen Transdermal Therapy and Blood Clots: What the Research Says

Updated: Aug 9, 2024



Hormone Replacement Therapy (HRT) is a standard treatment for menopausal symptoms, but concerns about the risk of blood clots have made many women hesitant to pursue this option. However, recent studies have highlighted that the method of estrogen delivery can significantly impact the associated risks. Notably, transdermal estrogen therapy has been shown to have a lower risk of causing blood clots compared to oral estrogen therapy.


Understanding Estrogen Therapy

Estrogen therapy is used to alleviate symptoms of menopause, such as hot flashes, night sweats, and vaginal dryness. It can also help prevent bone loss (osteoporosis) that can occur after menopause. Estrogen can be administered orally, transdermally (through the skin), or vaginally. Each method of administration has different implications for health risks and benefits.


Blood Clots and Oral Estrogen

Oral estrogen therapy has been associated with an increased risk of venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE). This increased risk is thought to arise because oral estrogen passes through the liver first, where it can increase the production of clotting factors. A significant body of research has documented this risk:

  1. The Women's Health Initiative (WHI) Study: This landmark study found that women taking oral conjugated equine estrogens had a higher incidence of VTE than those taking a placebo.

  2. The ESTHER Study: This French study showed that oral estrogen increases the risk of VTE by about four times compared to non-users.


Transdermal Estrogen and Blood Clots

Transdermal estrogen, delivered via patches, gels, or sprays, bypasses the liver and enters the bloodstream directly through the skin. This route of administration is associated with a lower risk of blood clots:

  1. Observational Studies: Several observational studies have indicated that transdermal estrogen does not significantly increase the risk of VTE. For instance, the ESTHER study found no increased risk of blood clots in women using transdermal estrogen compared to non-users.

  2. Meta-Analyses: A meta-analysis of various studies comparing oral and transdermal estrogen concluded that transdermal administration is associated with a lower risk of VTE. This analysis highlighted the difference in risk profiles between the two methods.

  3. Mechanistic Insights: Research suggests that because transdermal estrogen bypasses the liver, it does not increase the levels of clotting factors in the same way oral estrogen does.


Clinical Implications

The evidence suggesting that transdermal estrogen does not increase the risk of blood clots has significant clinical implications. It offers a safer alternative for women who require HRT but are concerned about VTE risk. Healthcare providers can consider this route of administration for patients with a higher baseline risk of blood clots, such as those with a history of thromboembolic events or genetic predispositions.


Conclusion

Transdermal estrogen therapy represents a promising alternative for women needing HRT, with a significantly lower risk of blood clots compared to oral estrogen therapy. As always, patients should consult with their healthcare providers to discuss the most appropriate treatment options based on their individual health profiles and risk factors.


References

  1. Women's Health Initiative (WHI) Study. (2002). Risks and benefits of estrogen plus progestin in healthy postmenopausal women. JAMA, 288(3), 321-333.

  2. Canonico, M., et al. (2007). Hormone therapy and venous thromboembolism among postmenopausal women. Circulation, 115(7), 840-845.

  3. Vinogradova, Y., Coupland, C., & Hippisley-Cox, J. (2019). Use of hormone replacement therapy and risk of venous thromboembolism: nested case-control studies using the QResearch and CPRD databases. BMJ, 364, k4810.

  4. Scarabin, P. Y., Oger, E., & Plu-Bureau, G. (2003). Differential association of oral and transdermal oestrogen-replacement therapy with venous thromboembolism risk. Lancet, 362(9382), 428-432.




By Dr Purity Carr

GP & Menopause Doctor

Harvey, WAs 6220

 
 
 

Comments

Welcome to Purity Health Women’s Menopause and Wellbeing Centre™

​

At Purity Health, we believe in living life to the fullest. Dr Purity Menopause Clinic, in association with Samy Medical Group, is dedicated to providing safe, evidence based information and care in perimenopause, menopause, histamine related conditions, and metabolic health.

​

We recognise that there are many myths and misunderstandings surrounding menopause and Hormone Replacement Therapy, HRT. One commonly repeated belief is that oestrogen causes breast cancer. This is an oversimplification and does not reflect the full body of evidence.

​

Here is the truth.

At Dr Purity Carr Menopause Clinic, we are committed to providing accurate information and personalised care.

Follow us on #drpuritycarr

Extensive evidence shows that for women within 10 years of menopause or under the age of 60, the benefits of HRT generally outweigh the risks.

​

For women who start HRT during perimenopause or within 10 years of menopause, there is often no need to stop purely based on age. Ongoing use should be individualised and guided by clinical review.

Even for women who are further beyond menopause or over 60, starting HRT may still be considered under the guidance of a knowledgeable practitioner, with careful assessment of risks and benefits.

​

A Broader Approach to Women’s Health

Dr Purity is a General Practitioner with a special interest in menopause care, taking a holistic, systems based approach to women’s health.

​

In addition to menopause, her work now includes:

Hormone health, including perimenopause and menopause
Histamine related conditions, including suspected mast cell activation patterns
Metabolic health, including weight management, insulin resistance, and inflammation
The interaction between hormones, the immune system, and the nervous system

Many women experience symptoms that do not sit neatly within one system. Hormones do not operate in isolation. There is often an overlap between hormonal changes, histamine activity, and metabolic dysfunction. This integrated approach allows for a deeper understanding of symptoms such as fatigue, anxiety, poor sleep, weight gain, brain fog, and chronic inflammation.

 

Dr Purity’s Focus on Care

Dr Purity focuses specifically on menopause, histamine balance, and metabolic health. She works to identify underlying drivers of symptoms and supports women through evidence based, personalised care.

Please note that Dr Purity does not replace your general practitioner. The experienced doctors at Samy Medical, part of the same medical system as Purity Health, are available to manage your broader healthcare needs.

bottom of page