Any medication (even over-the-counter drugs) can become deadly when taken in large amounts or in combination with other chemicals. Liquid medications taken by mouth (called oral dosing) are formulated for ease of swallowing. This is helpful for the elderly, anyone with difficulty swallowing, and children.
With liquid drug products, there is a grave concern that children will be given too much of a good thing. That’s why the Food and Drug Administration (FDA) has provided guidance for dispensing over-the-counter drugs. Drug companies that make liquid medications follow these guidelines by providing a cup, dropper, syringe, or spoon to measure out the right dose.
The idea in throwing away the cups is to avoid any misunderstanding on the part of the child as to their intended use. Children who are given a tasty liquid in the cup by a parent or guardian may decide to help themselves to more at a later time without adult supervision. Discarding the cups by throwing them away permanently may help in preventing unfortunate and potentially deadly drug overdoses.