Hello, Pre Menstrual Syndrome or PMS is the main cause of nausea before a period.This is common and is not usually a cause for concern. Nausea before a period could be caused (apart PMS) by many factors, including cramps, and pregnancy. You may feel nauseous as your body goes through hormonal changes before your period. The usual cramps,tiredness,breast tenderness and headache may also make you feel sick to your stomach and generally unwell. My advice for you is to try Chamomile. It’s said to be a digestive relaxant and may help with anything from flatulence to motion sickness to nausea and vomiting. Chamomile also has anti-inflammatory properties, which may help with other premenstrual symptoms like uterine cramping. My last advice is :Start Taking Prenatal Vitamins, Monitor Your Menstrual Cycle and Ovulation to find your fertility window every month,Eat Good Foods and Maintain a Healthy Weight.,Manage stress,exercise every day(But Not Too Much!),Stop Smoking and Drinking. You should wait to take a pregnancy test until the week after your missed period for the most accurate result. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Elona Xhardo, Endocrinologist