My doctor said 2.5ml only if they have a fever. My daughter is 2mths old and weighs 13lbs. My daughter is 20 months old, but she is 24 lbs. But even before, when she was just a little under that weight, we were using children's stuff, as the infant no longer did much for her. The mother gave her daughter Infant Tylenol, a formula that has a more concentrated level of the drug, whereas the doctor had told her to give Children's Tylenol, which is less concentrated. Add the doctor's suggestion of a child-size dosage—when the mother mistakenly used the more concentrated Infant Tylenol—and you have an overdose. Children's medicines are formulated to deliver the right amount of medicine to your little one. No matter the medicine or brand, always read and follow the label on the bottle before giving a dosage. We use cookies to give you the best possible experience on our website. By continuing to use this site you consent to the use of cookies on your device as described in our My doctor said that I can give my 2 month old baby tylenol after the vaccines as she may develop a fever and may get cranky. I forgot to ask the doctor for the dosage. For a parent it is understandable to be concerned when your little one has a fever. Learn more about helping to keep your child comfortable. Review the Infants’ and Children’s TYLENOL® dosage chart to better understand how to administer acetaminophen to your child based on their weight or age. When to Give Tylenol. Tylenol, also known as acetaminophen, can reduce your little one’s fever and ease any discomfort. At 2 months, though, if your baby runs a fever over 100.4 degrees or seems to be in much discomfort, you should talk to your pediatrician. Infant Tylenol Dosage Chart by Weight You’ll notice on the bottle of Infant Tylenol that it doesn't give dosages for children under 2 years old, but instead says to call your doctor. She'll be able to recommend whether or not to give Tylenol and what the correct dosage should be based on baby's weight.