Grandparents' medicines, such as heart or diabetes pills, can be very toxic to a young child. Once you have identified the potentially dangerous products in your home, you need to know the basic rules for protecting children from poisoning. Keep household products and medicines out of reach and out of sight of children. Keep them locked up, if possible. Don't leave hazardous products unattended, even to just answer the phone.
Children act fast . . .
So do poisons. If you must store chemicals under the kitchen sink, get child protective latches for the cabinet doors. Keep products in their original, child-resistant containers. Properly re-close the containers. Otherwise, they aren't child-resistant.