Why do you feel nauseous after you poop?

Answer 1

It is possible you are having a vasovagal response. Among people with vasovagal episodes, the episodes are typically recurrent, usually happening when the person is exposed to a specific trigger, in your case, a bowel movement. There are a lot of other triggers including urination, hunger, seeing blood, abdominal bearing down, etc. When experiencing a vasovagal response the individual frequently experiences symptoms such as lightheadedness, nausea, the feeling of being extremely hot (accompanied by sweating), ringing in the ears (tinnitus), uncomfortable feeling in the heart, fuzzy thoughts, etc.

When you experience the trigger (your bowel movement) it can directly or indirectly activate a portion of the brainstem which then enhances the parasympathetic nervous system at the same time the sympathetic nervous system is being reduced. In most people there is a decrease in heart rate and blood pressure. In some cases it can result in fainting (vasovagal syncope). The decrease in blood pressure and reduced heart rate is what makes you feel sick.