Fainting on the toilet may be caused by squatting for too long, exerting too much, malnutrition and other reasons. 1. Squatting for too long: because the toilet is a long time in the squatting position, easy to lead to the accumulation of blood in the lower part of the body, when suddenly stand up, it will lead to postural hypotension, insufficient blood supply to the brain, which leads to fainting. 2. Excessive force: when going to the toilet to stool, if too much force is easy to make the blood pressure rise, causing the coronary artery plaque off or spasm occlusion, resulting in insufficient blood supply to the myocardium, hypoxia, thus causing fainting. 3. Malnutrition: If long-term intake of nutritional deficiencies, easily lead to anemia, slowing down blood circulation may appear low blood pressure, toilet squatting up and aggravate the symptoms of low blood pressure, thus fainting in the toilet. Fainting on the toilet may also be caused by other reasons, the patient should go to the hospital in time to carry out relevant examinations to identify the cause of the disease for standardized treatment.