The Food and Drug Administration says a Johnson & Johnson and Bayer AG drug helps prevent deadly blood clots in patients getting hip or knee replacement, but it also puts them at risk for serious internal bleeding.

The name of the drug is Rivaroxaban and is sold under the brand name Xarelto in Europe, where it was approved last year.

“The evidence that administration of rivaroxaban (Xarelto) could lead to bleeding events in significantly more patients relative to enoxaparin amplifies this safety concern for rivaroxaban,” the FDA wrote in one review.

The product is pending FDA approval for short-term use to prevent blood clots in patients undergoing hip or knee-replacement surgery.  An FDA panel will be asked to vote on whether the drug carries a favorable risk- benefit profile. If the answer is affirmative, it amounts to a recommendation that the agency approve the drug, while a negative answer would suggest regulators should reject the drug.

If cleared, it would be the first time an oral anticoagulant drug is sold in the United States since the FDA approved warfarin in 1954.

 Documents released by Johnson & Johnson on Tuesday said the benefits of Xarelto outweighed its risks, adding that the company would take steps to monitor potential problems after approval. Furthermore, Bayer spokesman Alexander Siedler said the company was confident it could address FDA’s concerns.

The FDA will ask for advice from its panel on Thursday. The agency usually follows the panel’s recommendations, but not always.