Common pain relievers may dilute power of flu shots

With flu vaccination season in full swing, research from the University of Rochester Medical Center cautions that use of many common pain killers – Advil, Tylenol, aspirin – at the time of injection may blunt the effect of the shot and have a negative effect on the immune system.

Richard P. Phipps, Ph.D., professor of Environmental Medicine, Microbiology and Immunology, and of Pediatrics, has been studying this issue for years and recently presented his latest findings to an international conference on inflammatory diseases. (http://bioactivelipidsconf.wayne.edu/)

"What we've been saying all along, and continue to stress, is that it's probably not a good idea to take common, over-the-counter pain relievers for minor discomfort associated with vaccination," Phipps said. "We have studied this question using virus particles, live virus, and different kinds of pain relievers, in human blood samples and in mice -- and all of our research shows that pain relievers interfere with the effect of the vaccine."

A study by researchers in the Czech Republic reported similar findings in the Oct. 17, 2009, edition of The Lancet. They found that giving acetaminophen, the active ingredient in Tylenol, to infants weakens the immune response to vaccines.

Phipps' research has tested whether production of antibodies using a cell culture system was blunted by over-the-counter pain relievers. He found that a variety of pain relievers – even though Tylenol and Advil have different ingredients -- seemed to dilute the production of necessary antibodies to protect against illness.

Many of the pain relievers in question are classified as NSAIDs or nonsteroidal anti-inflammatory drugs, which act in part by blocking the cyclooxygenase-2 (cox-2) enzyme. Blocking the cox-2 enzyme is not a good idea in the context of vaccination, however, because the cox-2 enzyme is necessary for the optimal production of B-lymphocytes.