NSAID is Non Steroidal Anti-Inflammatory Drug
hydrocodone is an insaid used for swelling and pain
Jem says this because he is starting to realize that Boo Radley chooses to stay inside to avoid the prejudice and mistreatment he would face from the judgmental people in their community. Boo may feel safer and more comfortable hiding away from the outside world to protect himself from potential harm or misunderstanding.