How long does it take for a body to go back to normal after a 5 day course of 50mg prednisone without tapering the drug?

No taper needed: With steroids its all about the duration of time on the med. Our own bodies make cortisol which is basically what is in the steroid pill. Generally if someone takes a steroid pill for 3 weeks or longer they will require a taper. This is because the body will stop producing the cortisol with continued exogenous replacement. Only 5 days doesnt need a taper. Pred should be out of your body in 2 days.

A few more days: It may take a few more days before the effects of prednisone dissipate following discontinuation. It may also take a couple of days after taking it to provide noticeable effects .