If you search by how much does it take to od from certain medicines, you will often find answers, but these anwers are typically incorrect. What is correct is a careful scientific study from Harvard called "Lethality of Suicide Methods", which shows a success rate for drugs/poison at 1.5%. This study is from 1989 - 1997, so it doesn't include Sn, which has become more popular in recent years. You can find this study by searching for the title online. Most of the deaths in this study were from opioids. In a different study I just read online 80 people were admitted to the hospital for attempting suicide by acetominophen and none of them died. 13 were admitted for an accidental overdose and 2 of them died, possibly because they waited longer to seek treatment. This was from a study by the National Library of Medicine published in 2002. I searched on google using "suicide by tylenol" and this was the second thing that showed up.