Washington, Nov 4 Using common painkillers - Advil, Tylenol, aspirin - at the time of getting flu shot may weaken the effect of the injection and have a negative effect on the immune system, according to a research from the University of Rochester Medical Center.

Dr. Richard P. Phipps has been studying this issue for years and recently presented his latest findings to an international conference on inflammatory diseases.

"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. 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," said Phipps.

The researchers tested if over-the-counter pain relievers blunted production of antibodies using a cell culture system.

They 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.

Thus, when a person takes a medication to reduce pain and fever, he or she might also inadvertently reduce the ability of B cells to make antibodies.

The researchers also showed that timing of the administration of pain relievers is important as well. (ANI)