Rajecki also gives Tylenol, or acetaminophen, to her kids after a shot to prevent fever. Doctors tell her it's common.
But new research shows that combo may backfire.
"It directly inactivates a key enzyme in the B cells, and those are the cells that make the antibody," said Dr. Richard Phipps, an immunologist at the University of Rochester Medical Center.
Phipps says drugs like Tylenol and ibuprofen dilute vaccine potency. A recent European study of nearly 500 infants found the same thing.
"All the infants that got the Tylenol on the day of vaccination, almost every single one of them made less antibodies to a whole variety of vaccinations," said Phipps.
Here's what moms need to know: If junior is fussy after a shot, call your doctor to see if a pain reliever is the right move. And never give any child aspirin for a fever. Experts say a fever is a key immune response to infection.
Bottom line: a slight fever is okay. Now that she knows, Rajecki can get back to having fun with her kids: a key perk in this full-time career.
Adults getting vaccines, including flu shots, should also think twice before taking a post-vaccination dose of pills. Still, Phipps does stress those medications should be given to those who develop a fever over 102 degrees after a vaccination.