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Dysmenorrhea or painful periods are experienced by many women. The underlying causes could be many and it is difficult to comment on exact cause without further evaluation. She should consider visiting her doctor/gynecologist at the earliest for further evaluation. Taking antispasmodics does help with dysmenorrhea. If there are any other problems associated, she might need to get started on other medications too (other than the antispasmodic she is taking) to help with better control of the symptoms.
Take care.