Nausea during menstruation is caused by an increase in prostaglandins. The prostaglandins in the endometrium increase significantly during menstruation, causing the uterus to contract, resulting in a feeling of discomfort and swelling in the lower abdomen, and the increased prostaglandins enter the bloodstream. This increase in prostaglandins enters the bloodstream and travels to other organs, such as the digestive tract, including the stomach, causing stomach cramps that can lead to nausea and even vomiting, among other digestive symptoms. Significant nausea requires treatment, such as getting enough rest and sleep. Avoid eating cold, cold, hard or spicy foods to avoid stimulation of the stomach. In addition, if nausea and vomiting are obvious, oral medications to relieve stomach discomfort, such as gastroflucan, can be taken to regulate them.