The biggest problem with these classes of drugs, is that people ACCIDENTALLY overdose.

They will take their pills per their prescription, then later, forget they took them, and then take them again.

Unfortunately, I've seen this time and time again. One way to avoid this is to have a chart with your medications, so you can check off what you've taken and when you've taken it. This way, if you inadvertently go back to take something twice, you've got your record to prevent you from doing so.
Best,
Okie