Does having asthma increase my odds of developing venous thromboembolism or deep vein thrombosis?
Asthma is a chronic lung condition that causes airway inflammation. Research suggests that inflammation may also increase the risk of blood clots. A large meta-analysis of observational studies found that people with asthma have about 1.6 times higher odds of developing venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE). The risk appears strongest for PE, with odds about 2.4 times higher. While this does not prove asthma causes clots, the link is consistent across many studies.
What the research says
A 2025 systematic review and meta-analysis pooled data from multiple observational studies and found a significant association between asthma and VTE. Specifically, asthma was linked to 1.61 times higher odds of overall VTE, 1.56 times higher odds of DVT, and 2.41 times higher odds of PE 6. The association was strongest in cohort studies (OR 4.21) and varied by region, with the highest risk in Asia (OR 3.19) 6. These findings suggest that asthma may be an independent risk factor for blood clots, possibly due to chronic inflammation affecting blood vessels and clotting factors.
Other studies support the idea that respiratory conditions can raise VTE risk. For example, a 2021 study found that hospitalization for respiratory infection increased the risk of VTE readmission compared to asthma or cellulitis 8. Another study showed that COVID-19 hospitalization increased the risk of new VTE by about 1.9 times 10. While these studies focus on infections, they highlight that respiratory inflammation can trigger clotting.
It is important to note that the meta-analysis on asthma and VTE was based on observational studies, which can show association but not cause. The authors called for more research to understand the underlying mechanisms 6. However, the consistency of the link across different study designs and populations strengthens the evidence.
What to ask your doctor
- Given my asthma, should I be screened for VTE risk factors?
- Are there any specific symptoms of DVT or PE I should watch for?
- Could my asthma medications affect my clotting risk?
- Should I take any preventive measures, especially during travel or after surgery?
- If I have other VTE risk factors, do I need blood thinners?
This question is drawn from common patient questions about Pulmonology & Critical Care and answered using cited medical research. We do not provide individualized advice.