I take bout less than 5pills of ibuprofen a month for menstrual cramps & heard could be bad for your body in time? is this true?

Reasonable: You are taking reasonable amounts of Ibuprofen which should do no harm as long as they're taken with food and you have no ulcers, esophageal, or gastric inflammation.

No, it's safe: Ibuprofen at 600-800mg every 8 hours as needed for the duration of the menstrual period (ideally only 5 days or so, and less if you don't need that much) is very effective, safe treatment for menstrual pains. Too much Ibuprofen can sometimes cause an ulcer, or inflammation of the esophagus or stomach, so you don't want too much. Less than 5 pills a month sounds very very safe.