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Nausea and dizziness during menstrual periods could be due to dehydration, hormonal changes, infective causes, anemia etc. Take adequate rest. Drink plenty of water. Maintain healthy diet and lifestyle. If the symptoms persist or get worse, visit your doctor/gynecologist for further evaluation and assistance. Treatment as appropriate (based on examination findings and investigation results) would be started to help you control the symptoms. Be in regular monitoring and follow-up with your treating doctor/gynecologist and report any new/abnormal symptoms immediately.
Take care.