On Tuesday, U.S. health regulators demanded stronger warnings on four prescription drugs used to treat rheumatoid arthritis, Crohn's disease and other conditions. It happened after a large number of patients contracted fatal fungal infections and, consequently, passed away.

The medicines – Humira, Enbrel, Remicade and Cimzia - suppress the human immune system to avoid harming the body. People diagnosed with rheumatoid arthritis use them because they ease the pain caused by swollen and sore joints. However, as the FDA’s Dr. Jeffrey Siegel said, the treatment is “a double-edged sword,” for the reason that another consequence of taking the drugs is that the body’s ability to defense against infections decreases.

The new warnings have been posted Friday on the FDA’s Web site, Bloomberg reported.

According to Siegel, the U.S. agency started worrying following the discovery of doctors allegedly ignoring histoplasmosis, an infectious disease caused by the fungus. There have been reported 240 cases in which patients took one of the aforementioned drugs and developed this infection, The New York Times wrote. Among them, 45 - meaning about 20 percent - passed away.

On several of the medicines’ labels, one can already find "black box" cautions regarding the risks fungal and other infections pose. Nevertheless, the Food and Drug Administration required the drugs’ manufacturers to make the labels more consistent and to be more emphasized in order to point out more to histoplasmosis, Siegel asserted, Reuters reported.