Why can prescription drugs be considered as dangerous as illegal drugs?

(pick an answer)

If someone is addicted to illegal drugs or uses prescription drugs it will have the same result.

They are not addictive, but can still be dangerous.

They can be addictive and possibly deadly, just like illegal drugs.

They can be addictive like illegal drugs, but are not dangerous.

They can be addictive and possibly deadly, just like illegal drugs.