The U.S. Food and Drug Administration, or FDA, warned in 2011 that people who take tumor necrosis factor-alpha blockers, also known as anti-TNFs or TNF-blockers, may be at risk of infection from the bacteria Legionella and Listeria.

After reviewing cases of infection in patients treated with the drugs, the FDA is strengthening the drugs’ boxed warning labels to include the two bacteria.

Anti-TNFs, a type of biologic product, are used to treat rheumatoid arthritis, or RA, ankylosing spondylitis, psoriatic arthritis, juvenile arthritis and several other conditions.  The new warnings will be added to labels for infliximab (Remicade), etanercept (Enbrel), adalimumab (Humira), certolizumab pegol (Cimzia), and golimumab (Simponi).

Serious infections – from bacteria, fungi, viruses, mycobacteria (including tuberculosis) and other opportunistic pathogens – are a known risk of anti-TNFs, which can compromise the immune system’s ability to fight infections. Patients older than 65 and those taking other immunosuppressive drugs may be at greater risk of infection.

The added warning may help patients with these infections get treatment more quickly, according to the FDA. In the past, healthcare professionals weren’t always aware of the risk of certain infections, leading to delayed treatment. 

“Any product we use to treat rheumatoid arthritis, because it affects the immune system, always has the potential for infection,” says David Pisetsky, MD, PhD, chief of the division of rheumatology, allergy and clinical immunology at Duke University Medical Center. “The difference is there are now two other organisms that we have to be concerned about. So, if a patient gets sick, you add into your thinking, ‘Could it be Legionella or Listeria?’

Jeffrey Curtis, MD, director of the Arthritis Clinical Intervention Program at the University of Alabama at Birmingham, agrees. “All the FDA has done is called out two specific infections among all the other ones that physicians have been thinking about,” he says.

“The take-home message for patients is that they should not have new concerns or worries about the safety of these medications,” says Dr. Curtis, who is also an associate professor of medicine at UAB and a former Arthritis Foundation-funded researcher.