There are a lot of people that accidently overdose everyday. Some get help in time and others don't. Overdosing on a drug is as simple as taking it on an empty stomach or taking all of your medications together.
Example: if you take too many aspirins within a certain amount of time, you can kill yourself. How? Because of the way your liver breaks down the pharmacology of the aspirin. There are a lot of people who die of alcohol poisoning everyday. Is it intentional? No. It's just a horrendous outcome of the way your body metabolizes certain chemicals.
It is also believed that Whitney died from organ failure and was dead before she went underwater. Because her lungs were full of water and there was no evidence of a gag reflex during the autopsy.
There are a lot of us who are ticking time bombs everyday because of the amount of time it takes our medications to metabolize in our bodies. Sometime it only takes hours and for some other drugs it takes days. Some drugs are fast acting and some are slow acting. Meaning they build up in your system and all it takes is the consumption of the wrong thing and BAM!! You're in the emergency room wondering what the heck is going on.
All drugs come with a warning. Over the counter drugs. Prescription drugs. and illegal drugs. Next time you see a commercial about a drug listen very carefully to the possible side effects. Next time you get a prescription filled read the drug info sheet and see all of the possible side effects that could occur.
It's like you're damed if you don't take the medication and there is a slim possibility that you'd be dead or near death if you do. You would never think that there is a possibility that the medication you are taking may make you suicidal or could cause you liver damage. Or that you would have a severe allergic reaction to a chemical in the medication you are taking.
We are all living life on the edge of a razor with a puddle of alcohol waiting for us at the bottom.