A recent article in Lancet was quite thought provoking as it studied the common practice of giving infants a dose of acetaminophen (Tylenol) with their routine immunizations.

Many parents and some pediatricians routinely dose their infants with acetaminophen prior to receiving their vaccines at two, four and six months of age. In the study of 459 infants from 10 different centers in the Czech Republic, patients were randomized to either receive three doses of acetaminophen every six to eight hours at the time of vaccination or no acetaminophen. The researchers then looked at both the reduction of febrile reactions post vaccination and at antibody titers among the two groups.

Interestingly, there were both some expected and some not so expected results. Not surprisingly, the group that received acetaminophen had a lower incidence of fever post immunization. Of those that received acetaminophen 94 out of 226 (42 percent) developed a fever, compared to 154 out of 233 (66 percent) in the non-treated group after their primary immunization series. After booster vaccination 64 out of 178 (36 percent) in the treated group and 100 out of 172 (58 percent) developed fever. So the widespread perception by both many parents and doctors that routine acetaminophen use with vaccination does reduce the incidence of fever was supported.

The most interesting result of this study was the vaccine antibody response in the acetaminophen treated group. Surprisingly, antibody responses to several of the routinely administered vaccines (including tetanus, diphtheria, h. flu, and pneumococcal serotypes) were lower in the group who received routine acetaminophen. This was also seen after booster doses of the same vaccines between 15 to 18 months of age.

The hypothesis is that acetaminophen may reduce the inflammatory response and that this may also induce less of an immune response.

So, it would seem prudent to no longer encourage routine use of acetaminophen with vaccines unless a baby develops significant fever, or is at risk for fever and febrile seizures. As a parent you are always trying to “protect” you child, and this would include any pain or fever that might develop with vaccination. Now we have science to show how this may actually provide less protection, against disease. Thought provoking!

That’s your daily dose, we’ll chat again tomorrow.