A couple from Ohio has filed a Xarelto lawsuit against Janssen Pharmaceuticals, arguing that the drug maker’s blood thinner caused life-threatening bleeding side effects.

This Xarelto lawsuit was filed by plaintiffs Charlotte S. and Gerald S. According to the couple, Charlotte was prescribed the drug in February 2012 after she had knee surgery.

This surgery put Charlotte at risk for deep vein thrombosis and pulmonary embolisms, two possible blood-clot related complications. Xarelto was supposed to reduce her risk of these complications from her knee surgery.

However, the Xarelto lawsuit asserts that Charlotte suffered from uncontrolled bleeding from Xarelto on Feb. 23, 2012, mere days after she began taking Xarelto. This was a medical emergency and required intensive medical care to save her from bleeding to death.

Xarelto is a type of drug called an anticoagulant or blood thinner. Anticoagulants are designed to make it harder for patients to form blood clots. While blood clots are a normal part of the healing process, it can misfire.

When a blood clot forms within the body, it can lodge within the blood vessels that feed critical tissues, including the heart, lungs and brain. This would cause certain types of heart attacks, pulmonary embolisms, and stroke.

Drugs like Xarelto are designed to reduce the risk of these conditions. But all anticoagulants carry the risk of working too well and resulting in uncontrollable bleeding, and Xarelto lawsuits allege that Xarelto and other newer anticoagulants carry the risk of working too well.

All anticoagulants carry the risk of causing uncontrolled bleeding. When this happens, the patient loses the ability to form blood clots, and they can lose a life-threatening amount of blood from a very minor injury, including internal injuries. This may take the form of gastrointestinal bleeding or pulmonary bleeding.

But Xarelto lawsuits like this one allege that Xarelto and other newer-generation blood thinners are particularly dangerous for several reasons. First, Xarelto does not have a known reversal agent.

Older anticoagulants like Warfarin can be “turned off” in an emergency uncontrolled bleeding incident. The way this works is that when there’s an uncontrolled bleeding event, patients on Warfarin can be given a high dose of vitamin K to let the patient’s blood clot.

Additionally, older drugs like Warfarin require that patients routinely test their blood to make sure the drug is working right. Despite some research that Xarelto patients could benefit from such as blood testing, the makers of Xarelto have advertised Xarelto as not requiring blood tests.

The Xarelto Uncontrollable Bleeding Lawsuit is Case No. 1:15-cv-28, in the U.S. District Court for the Southern District of Ohio, Cincinnati Division.