New research suggests there may be a slightly greater risk for Xarelto uncontrollable bleeding for patients who take the blood thinner to treat abnormal heartbeat known as atrial fibrillation.

Most patients with the condition take a blood thinner to reduce the risk of stroke.

Although blood thinners help prevent stroke, they can also cause uncontrollable bleeding, which can be fatal, the researchers said.

Two newer drugs — Xarelto (rivaroxaban) and Pradaxa (dabigatran) — are newer alternatives to the older drug warfarin, a medication that is notoriously difficult to monitor.

Which of these newer drugs is safer, however, hasn’t been proven, said the U.S. Food and Drug Administration researchers behind the new study.

Blood Thinner Study

The new study about the possible higher risk of Xarelto uncontrollable bleeding was published online Oct. 3 in the journal JAMA Internal Medicine.

For the study, researchers led by Dr. David Graham, associate director of science at the FDA’s Center for Drug Evaluation and Research, collected data on nearly 119,000 Medicare patients with atrial fibrillation treated with either Xarelto or Pradaxa from November 2011 through June 2014.

The researchers found little difference in stroke risk among patients taking either Pradaxa or Xarelto. But, there was a small yet statistically significant increase in risk of bleeding in the brain and stomach of patients taking Xarelto.

And among certain patients 75 and older, Xarelto was associated with a small but statistically significant increased risk of death.

However, the study did not prove that Xarelto caused bleeding or death, just that there was an association.

What is Xarelto?

Xarelto is one of the newest blood thinners developed by Bayer and Janssen Pharmaceuticals. Blood thinners prevent dangerous blood clots that can obstruct the blood flow to the vital organs.

Unlike older anticoagulants like warfarin that require doctors to prescribe specific doses for each individual, Xarelto is prescribed in one uniform dose.

The FDA approved Xarelto for use in patients who have had knee or hip replacement surgery to reduce the risk of blood clots, reducing the risk of stroke in people with atrial fibrillation.

Following a fast-track regulatory review, the FDA approved the drug for general treatment of deep vein thrombosis (DVT) and pulmonary embolism.

Xarelto Side Effects

One of the most severe side effects of the blood thinner is Xarelto uncontrollable bleeding. When bleeding occurs near a major organ, such as the brain, lungs or kidneys, blood flow to that organ is interrupted, causing it to lose some or all of its functionality.

Because Xarelto prevents clotting, the hemorrhaging will continue until the drug is flushed out of the system.

While all blood thinners carry the risk of internal bleeding, older drugs like warfarin have emergency antidotes to prevent serious harm.

Xarelto does not have an antidote, and the drug cannot be flushed out of the system through dialysis. People who suffer uncontrollable bleeding while taking Xarelto can end up hospitalized, and the bleed may be fatal.

Xarelto Uncontrollable Bleeding Lawsuits

A growing number of Xarelto lawsuits have been brought by injured patients and their surviving relatives. They accuse the drug makers of putting their financial bottom line ahead of consumer safety by touting Xarelto as a safer blood thinner that does not require monitoring.

Bayer and Janssen are facing dozens of lawsuits involving people who say they were seriously injured or died from Xarelto uncontrollable bleeding.

The Xarelto lawsuits allege that users of the drug were not adequately warned about the risk of severe, potentially fatal bleeding, or Xarelto’s lack of an effective reversal agent.