My mom is of 47 years and her periods is regular and when it comes it lasts for about 6 days with last 4 days of heavy discharge. is it dangerous ?

Likely normal: I am wondering why you're asking this question for your mother. If this was her pattern for many years it is likely normal. Many women experience heavy bleeding, sometimes this can lead to anemia. For this reason blood counts should be checked periodically - probably at least annually. Iron supplementation may be necessary. Some medications may decrease bleeding (oral contraceptives) Good luck