One of the big selling points for the anticoagulant Xarelto (rivaroxaban) was the claim that, unlike warfarin, patients didn’t have to worry so much about food interactions and what they ate while taking the medication. With warfarin, patients must avoid a number of healthful foods, particularly nutrient-rich leafy greens such as spinach and kale.

The reason is that the Vitamin K content of these foods counteract the “blood-thinning” properties of the drug. This nutrient plays a prominent role in blood clotting, which is why patients who suffer from hemorrhaging while taking warfarin can be readily treated with large doses of Vitamin K. In addition, patients on warfarin are told to avoid eating grapefruit, as this decreases the body’s ability to metabolize the drug, rendering it ineffective.

According to the official product website, “Xarelto has no known dietary restrictions.” The promotion says:

XARELTO® doesn’t interact with vitamin K like warfarin does. So you can enjoy healthy options like leafy green vegetables and other foods rich in vitamin K whenever you like, without having to worry about them changing the way XARELTO® works.”

Well, rivaroxaban may not interact with vitamin K, but the claim that there are “no known dietary restrictions” is not entirely accurate. As it turns out, a 2012 article appearing in the Canadian Medical Association Journal (CMAJ) lists no fewer than 85 medications that had potential interactions with grapefruit and grapefruit juice – among them, apixaban (Eliquis) and rivaroxaban (Xarelto).

Xarelto was approved by the FDA only weeks before the CMAJ article was published.

In addition, an extensive 2013 review by the FDA indicated that “grapefruit juice may…increase plasma concentrations of Xarelto and should be avoided.”

While grapefruit is the only food currently suspected to interact with Xarelto, that still negates the manufacturer’s claim there are “no known dietary restrictions.” It may seem like a small detail, but for people who commonly eat grapefruit and are taking rivaroxaban, the consequences could be serious. Despite the fact that these concerns were published early on, there is still no warning about the consumption of grapefruit on Xarelto’s package label.

Bayer and Janssen Pharmaceuticals are still dealing with lawsuits over injuries and deaths caused by uncontrollable bleeding. In addition, a study comparing Xarelto with aspirin in the prevention of secondary stroke was canceled when the results didn’t turn out the way the manufacturers and sponsors at hoped (it showed that Xarelto was no more effective for this indication that aspirin).

It may seem like a minor oversight, but given Bayer’s history, it will not help the company’s credibility.

K.J. McElrath is a former history and social studies teacher who has long maintained a keen interest in legal and social issues. In addition to writing for The Ring of Fire, he is the author of two published novels: Tamanous Cooley, a darkly comic environmental twist on Dante's Inferno, and The Missionary's Wife, a story of the conflict between human nature and fundamentalist religious dogma. When not engaged in journalistic or literary pursuits, K.J. works as an entertainer and film composer.