The U.S. Food and Drug Administration (FDA) has ordered stronger warnings on four medications used to treat rheumatoid arthritis (RA), claiming the drugs can raise the risk of histoplasmosis, a potentially fatal fungal infection. The drugs-Enbrel, Remicade, Humira, and Cimzia-work by suppressing the immune system to keep it from attacking the body, but they also lower the bodys defenses to infection. The FDA became concerned after finding that of 240 reported cases of the infection, 45 patients died-about 20 percent. The infection mimics the flu and can have serious consequences if it isnt caught early and spreads beyond the respiratory system to other organs. The FDA has ordered that the risk of histoplasmosis be flagged in a "black box" warning in the drugs prescribing literature and recommends that patients call their doctors if they develop fever, cough, shortness of breath or fatigue, all of which can be signs of the fungal infection.