That does happen to some people. Although it happens often, it shouldn’t be taken lightly. Make sure you eat a diet rich in vegetables and fruit all the time, but especially when menstruating. Also, have the doctor check your hemoglobin, and try to start taking vitamins rich in iron, or even iron tablet if indicated. When you feel this way, always get up slowly so you don’t fall. If you’re at work and you need to sit, make sure you sit.