Naturally, children are adventurous and over-reaching. When it comes to picking objects, sticking them in their mouth, and going on to the next toy, they feel very comfortable. But when it comes to medicines, this is not safe.
Any pill-containing blisters or bottles are specially made to discourage little kids from opening them. This design serves as a secondary measure of security, the primary one being to keep drugs away from the reach of children.
There are over-wrappers and locking mechanisms in certain prescription packaging that can only be opened by performing a certain manoeuvre. The packaging of pharmaceutical drugs by such designs prevents overdosing illnesses and even death among kids of all ages.