The research, published in the journal Lancet, says infants given acetaminophen had an increased risk of developing asthma.
They also showed more symptoms of eczema and allergies than infants who were never given the painkiller.
Experts say it is too soon to blame the medication, but researchers suggest only using the drug to treat fevers of 101 degrees or higher.
They also remind parents never to give a baby aspirin, which can cause the potentially deadly condition Reye's Syndrome, a disease that attacks the organs.
