For an Epsom Salt bath to be effective you need to soak in the Epsom Salt bath for 15 to 20 minutes.
You can soak in the Epsom Salt Bath for 30 minutes if you want too.
Soaking in an Epsom Salt bath can help to relive constipation and help get your bowels moving as long as you're in the Epsom Salt bath for a minimum of 15 minutes.