I found it strange that Severide could be so casual about the fact that he has some painkillers at home that he could take. He was addicted to them in season one. It would be very unwise for him to take any now and he should know that. I wonder if this is a case of the writers' forgetting or if this was on purpose.
shareI think the last time was more about not wanting to go out on disability for his shoulder injury. He was taking a ton of pain killers so he could stay on the job. It had nothing to do with him wanting to get high.
shareHe developed a physical dependency on them after using them after being injured. He only abused them when Shay was nearly killed and only for a couple of days.
shareI remember when Shay got in the accident and she didn't want to move back with him until he gave up the pills. He said he would go cold turkey first and then if he couldn't kick it he would get help. So it was sort of implied that he had a little bit of a problem.
I caught this too. I wasn't sure if they would make him get hooked on them...or if they just forgot...but it was odd.