Hi,
You should not get a reaction, but having said that, everyone is different and I suppose it depends on the what pain meds you are taking. Anything is possible.
However, if you have had a cortisone injection and it has worked properly, you should not have to take pain meds for a few days. The cortisone should reduce the inflammation and when you reduce inflammation, you should also reduce pain.
Have you been getting any symptoms and of what type?
Hope this helps?
Sarah