How long after the penicillin shot for strep throat should I wait to go out? I got the initial shot on friday and went and got an additional steroid shot at the ER last night and I feel a lot better

Once . Once you have been on antibiotics for strep for 24 hours, you are no longer contagious. However, steroids can make you feel better even when you are still sick by dampening down your immune response, so take it easy!