Death by a cyanide pill is quite interesting I think. I have read a few accounts about people using this method. When reading about this I was trying to learn more about the pain, but there was no big focus on this matter in either of the texts. I will share with you what I rememeber.
Right now I am remembering 3 instances where a cyanide pill was used, all of them were used by Nazis at the end of WW2:
1.: Heinrich Himmler swallowed the pill right after being arrested by British troops in 1945. This happened during a body search. He did suffer pain, and the doctor present tried to save him but he died. How long his suffering lasted and how much he suffered was not described in detail.
2.: Hermann Goering swallowed the cyanide pill just a few hours before he was scheduled to be hanged in Nuremberg prison. He did this while lying in his bed. At this time Goering were under a 24 hours watch by prison guards, and the guard on duty sounded the alarm when he saw Goering's face start to twitch. My understanding is that he suffered pain, but I don't know how much suffering there was.
3.: When Adolf Hitler committed suicide (by shooting himself), his wife Eva Braun killed her self with a cyanide pill. There are no description of her death since only Hitler was present in the room, and they both died. But before they killed themselves they tested a cyanide pill on Hitler's dog. They must have been satisfied with how the dog died since she chose to use the pill for her own death.
As far as I know all these suicide pills were the same type. It was produced in The Third Reich and given to a lot of high ranking and important people. I have tried to obtain more information about these pills but so far I haven't been successfull.
At this time I will not reccomend using this method since I know too little about it. But I think this is very interesting and I want to learn more about it. I hope someone on this forum can help.
P.S.: Since these pills were made for the sole purpose of suicide I think the pain and suffering by this method is something that would have been considered by the manufacturer. They had access to a lot of different poisons and they chose cyanide. That makes me think the pain could be bearable… mayby.