Amgen Inc and Wyeth’s Enbrel arthritis and psoriasis drug will carry a new “black box” warning about the risk of serious infections that may lead to hospitalization or death, the U.S. Food and Drug Administration said on Thursday.

Enbrel is used to treat rheumatoid arthritis, plaque psoriasis, psoriatic arthritis, ankylosing spondylitis and juvenile idiopathic arthritis. The drug is made from a type of protein called a tumor necrosis factor (TNF) blocker that blocks the action of a substance made by the body’s immune system called TNF. People with the diseases listed above have too much TNF in their bodies. The drug was first approved in 2000 for rheumatoid arthritis and its use was later expanded to treat psoriasis and other rare autoimmune disorders.

Amgen and Wyeth both alerted doctors about Enbrel’s black box warning in a March 14 letter. Now the warnings appear on the FDA’s Web site.

“Patients who develop an infection should be evaluated for appropriate antimicrobial treatment and, in patients who develop a serious infection, Enbrel should be discontinued,” the FDA said in a statement on its Web site.

Enbrel’s label warns patients and doctors about tuberculosis, bacterial sepsis and other infections in patients taking the drug. The label also recommends teaching patients taking Enbrel about infection symptoms, monitoring them for infection during and after treatment with Enbrel and screening them for tuberculosis before and during Enbrel treatment.

The new warning was prompted by worldwide studies of more than 20,000 patients taking Enbrel. About 200 people developed tuberculosis, a bacterial lung infection. Approximately 14,000 Americans were diagnosed with the disease last year and, according to the federal Centers for Disease Control and Prevention, people with weakened immune systems are most likely to contract it.