Deadly Blood Clots Linked to Popular Mental Health Drug Combo of Clozapine and Fluvoxamine Raises Alarms
Nikhil Prasad Fact checked by:Thailand Medical News Team May 27, 2025 1 day, 17 hours, 9 minutes ago
Medical News: In a new and deeply concerning discovery, doctors from Graylands Hospital in Perth, Australia have reported two shocking cases of pulmonary embolism—a life-threatening type of blood clot in the lungs—linked to the use of clozapine and fluvoxamine. What’s most alarming is that both patients had no known risk factors for developing such clots.
Deadly Blood Clots Linked to Popular Mental Health Drug Combo of Clozapine and Fluvoxamine Raises Alarms
Clozapine is a powerful antipsychotic medication commonly used to treat severe schizophrenia, while fluvoxamine is an antidepressant used to increase clozapine levels in the body for better treatment outcomes. Together, however, this combination may create a dangerous recipe for blood clot formation even in seemingly healthy individuals.
This
Medical News report highlights findings that could have life-or-death implications for thousands of psychiatric patients worldwide.
Two Healthy Men Suddenly Struck by Lung Clots
The first patient, a 46-year-old man with no history of smoking, obesity, or any health problems, was admitted for untreated schizophrenia. After failing to respond to other medications, he was placed on clozapine, along with fluvoxamine to boost effectiveness. Everything seemed fine until four weeks into treatment when he suddenly experienced dizziness, rapid heart rate, and dangerously low oxygen levels. Imaging confirmed massive bilateral pulmonary embolism. He required emergency care, including oxygen and blood thinners. Miraculously, he made a full recovery.
The second patient, a 49-year-old man with delusional disorder, had a similar story. With no underlying health issues and a healthy body weight, he too was given clozapine and later fluvoxamine. After 10 months on this combination, he developed sudden breathing difficulties and was rushed to the hospital. Scans showed extensive clots in both lungs. Once again, no other risk factors were found. After discontinuing clozapine and being treated with blood thinners, his symptoms resolved.
How Can a Mental Health Drug Cause Dangerous Clots
The researchers, Dr. Tobias Richards and Dr. Katinka Morton from the Department of Forensic Psychiatry at Graylands Hospital, reviewed previous studies and theories. They found growing evidence that clozapine, even by itself, may increase the risk of blood clots through several mechanisms. These include increased platelet activity due to clozapine’s effects on serotonin receptors, as well as a general inflammatory state caused by metabolic changes from the drug. Some studies even showed an increase in specific antibodies that may trigger clotting.
Although clozapine is known to cause sedation, weight gain, and reduced movement—all of which are indirect clotting risks—the two men in this study were not obese and were active. Moreover, one theory explored in this report is that fluvoxamine may intensify the clotting risk by elevating clozapine levels beyond a safe threshold. In both cases, the patients were taking
moderate doses of clozapine but had relatively high serum levels when the embolism occurred.
Why Doctors Need to Be Extra Cautious
Doctors often overlook pulmonary embolism in psychiatric patients because clozapine’s side effects—like rapid heartbeat or low blood pressure—can mask the signs of a clot. This makes diagnosis difficult. And since many psychiatric patients struggle to communicate their symptoms, problems may be detected too late.
Another troubling aspect is the lack of official guidance. In Australia, for instance, the medication information sheet for clozapine does not list previous blood clots as a contraindication. This could result in psychiatrists unknowingly placing vulnerable patients at risk.
Key Takeaways from the Cases
Both patients were relatively young, physically healthy, and had no clotting risk factors like smoking or family history. Their only common link was the use of clozapine and fluvoxamine. One developed a clot just four weeks into treatment, while the other was affected after ten months.
Interestingly, both men were on moderate doses of clozapine, yet had very different clozapine blood levels. This further supports concerns that blood clots may not depend purely on the dose but may relate to how the body processes the drug or interacts with fluvoxamine.
Conclusion
These two cases highlight an urgent need for the psychiatric and medical community to take blood clot risks from clozapine—especially when combined with fluvoxamine—much more seriously. Physicians must be vigilant for early warning signs and consider regular screening for clotting disorders before starting such therapies. Prophylactic blood thinners or alternative medications might need to be considered in high-risk patients, even those with no traditional risk factors.
Given how subtle yet fatal pulmonary embolisms can be, these findings should prompt a reevaluation of treatment protocols and informed consent discussions. There’s also a need for more research into how fluvoxamine might raise clotting risks when used alongside clozapine.
The study findings were published in the peer reviewed journal: Case Reports in Psychiatry
https://onlinelibrary.wiley.com/doi/10.1155/crps/2411667
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