is not the right medicine to make the periods regular. But taking it will not harm your daughter. You have not mentioned the age when your daughter started having her periods. periods are generally irregular for first 2-3 years. this is absolutely normal and you do not need to give any treatment. Stopping this medicine does not cause weight gain. nevetheless you must keep your daughter's weight under controll. To control her weight involve her in some exercise like jogging, aerobics
or swimming etc. Avoid junk food and plan a healthy diet for her. By the time your daughter reaches 16- 17 years her periods will automatically become normal, if they still do not then you need to consult a doctor.