The Oxypowder will help your body to become more balanced into alkaline state over of time. The soreness that you are referring to is due the acidic nature of your bowel movements at the current time. You can help the process by trying to eat a diet that is more alkaline. If you have access to a library, I would check out the book called Prescription for Nutritional Healing, there is a section acid/alkaline imbalance. This section actually lists foods that will make your body more alkaline which is the goal.I have been taking Oxypowder over three years, in the beginning I also experienced soreness as well. I also changed my diet, eliminated soft drinks and increased my water intake. I have found that the only time that I have soreness now is if I eat spicy foods.