system
Given the following post, respond as if you're commenting on Reddit:
human
eli5: what heroin withdrawals feel like

Because I just watched Gene Hackman writhing all over the floor of a Marsielles jail cell and it looks awful. But what does it feel like exactly? Is it pain? Is it an itch? 

edit: wow this blew up! Thanks for all the insightful answers, it sounds absolutely fucking awful. With that knowledge, I think Gene Hackman really did a killer job!
gpt
Constant alterations in temperature, one moment you're overheating and sweating, 10 seconds later you're freezing cold plus the sweat. No appetite, pain, sneezing and general increase in fluid production like tears and nose drip. Diarrhea. Nausea. Insomnia. Irritability. 

source: currently living it!

**edit:** these "supportive comments" are all annoying and stupid.