A few things to know:

• McNeil Consumer Healthcare, the Johnson & Johnson unit that makes Tylenol, and the Food and Drug Administration both knew for 15 years about the sometimes-lethal confusion over its Tylenol products for infants and children. Drop for drop, the strength of Infant’s Tylenol used to far exceed that of Children’s Tylenol. By confusing the products and administering too much of the infant’s version, parents or caretakers could inadvertently overdose their children.

• Aware of the problem, McNeil continued to sell the products as it pleaded with the Food and Drug Administration to add a dosing label that the company believed would solve the problem. The current label instructs consumers to call a doctor to get dosing instructions for children under two — but there is ample evidence that even healthcare providers sometimes mix up the products and give the wrong dosing instructions. McNeil wanted the FDA to add specific instructions by age and weight.

As of 2011, McNeil and other acetaminophen makers voluntarily agreed to stop selling two different concentrations of pediatric products. Today, infants’ and Children’s Tylenol have the same concentration, eliminating the potential confusion between two formulations.

• The FDA, has yet to take formal action. It has not mandated a single concentration. Nor has it decided whether to implement McNeil’s suggestion to add dosing information for kids under two.