Final answer:
To prevent accidental poisoning, medicines should be stored in a locked cupboard, as this keeps them out of children's reach and reduces the risk of serious harm.
Step-by-step explanation:
To prevent accidental poisoning of a child, parents are instructed by the home health nurse to place medicines in a locked cupboard. This is the safest option because it ensures that medications are kept out of the reach of children, thereby reducing the risk of accidental ingestion and poisoning.
The effects of poisoning can range from a short-term illness to more serious consequences such as brain damage, coma, or even death, emphasizing the critical nature of safe storage practices.