Study Questions Whether Side Effects of Xeljanz, Similar Drugs, Increase Blood Clot Risks

Researchers said neither the side effects of Xeljanz, or similar drugs appear to increase the risk of venous thromboembolism-related injuries.

Following FDA label warnings added last year, the findings of a new study appears to raise questions about whether the side effects of Xeljanz and similar rheumatoid arthritis drugs, known as JAK inhibitors, actually increase the risk of blood clots.

Xeljanz (tofacitinib) was introduced by Pfizer in 2012, as the first member of the JAK inhibitors class of medications, which joined a lucrative market that generates billions in annual sales for treatment of rheumatoid arthritis, psoriatic arthritis and ulcerative colitis. The class of medications now also includes Olumient (baricitinib), which was introduced in 2018, and Rinvoq (upadacitinib), which was introduced in 2019.

Last year, the FDA announced new label warnings about the Xeljanz heart and cancer risks, after evaluating data from a large randomized clinical trial funded by the drug maker, which found users of the drug experienced more blood clot-related injuries, cardiovascular events, as well as cancers and death. As a result of the findings, the agency required a label update for Xeljanz, as well as all other drugs in the same new class of medications.

There are now a number of Xeljanz lawsuits being pursued by former users, each raising similar allegations that the drug makers introduced and aggressively marketed the new treatment without warning users and the medical community about the potential health risks.

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Xeljanz Lawsuits

Side effects of Xeljanz linked to risk of cancer, heart attacks, pulmonary embolism, deep vein thrombosis, blood clots and death.


After evaluating preliminary data from a Xeljanz clinical trial released in February 2019, the drug manufacturer Pfizer announced that year that patients receiving 10mg doses of Xeljanz twice per day were found to have a significantly higher risk of experiencing pulmonary embolisms and had an overall higher rate of mortality when compared to patients taking 5mg doses of Xeljanz for ulcerative colitis.

The FDA issued a warning about the Xeljanz blood clot problems after the initial Pfizer results were released.

However, in a study published late last month in JAMA Dermatology, Taiwanese researchers raise doubts about whether JAK inhibitors, like Xeljanz, Jakafi and Olumiant, actually raise the risk of venous thromboembolism events caused by blood clots.

In this new study, the researchers conducted a systematic review and meta-analysis of two cohort studies and 15 randomized clinical trials involving nearly half a million participants who suffered from atopic dermatitis (AD0. They looked at whether the condition itself, or treatment with JAK inhibitors, increased the risk of blood clots and venous thromboembolism (VTE).

According to their findings, they did not see an increase in VTE among AD patients given Xeljanz or similar drugs.

“The results of this systematic review and meta-analysis suggest that the currently available evidence does not detect an increased risk of VTE associated with AD or treatment with JAK inhibitors,” the researchers concluded. “These findings may provide a reference for clinicians in prescribing JAK inhibitors for patients with AD.”

Xeljanz Side Effects Lawsuits

After Xeljanz was introduced, Pfizer marketed the drug and pushed build market share among number of blockbuster rheumatoid arthritis treatments that were already on the market, which included Humira, Enbrel and other TNF inhibitors.

Xeljanz was advertised as a safer and more convenient treatment option, and quickly grew to become a top selling drug, with annual sales of more than $2 billion worldwide. However, concerns about serious Xeljanz side effects first emerged after preliminary data was released from a post-marketing study conducted by the drug maker.

According to allegations raised in a number of Xeljanz blood clot lawsuits, the drug maker ignored serious risk signals associated with their new treatment and put their desire for profits before consumer safety by failing to adequately research the new medication or warn about the side effects.

There are now a growing number of former users pursuing a Xeljanz lawsuit against the drug maker, after being diagnosed with cancer, heart attacks, strokes, pulmonary embolism, deep vein thrombosis or other injuries that may have been avoided if earlier warnings had been provided about the potential side effects.


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