Hi, You are having irregular menstruation because of the female sex hormones imbalance in your blood. The Althea medicines prescribed to you are hormonal pills. Taking these pills regularly will resolve the cysts in your ovaries, will regulate hormone levels in your blood and this will ultimately make your menstrual cycles regular. There has been recent research that suggests that giving Metformin to PCOS patients is highly beneficial in treating the disorder. So your doctor prescribed you metformin. Thus, I would advise you to start with both Althea and Metformin in prescribed dosage and the way that has been explained to you by the prescribing doctor. Diarrhoea is not observed as side effect of any of this medicine. However, if you have the same side effect again and you feel that these medicines do not suit you, then you can consult your gynecologist to prescribe you alternative medicine. There are many alternatives to Althea and if one does not suit you, you can switch to other. I hope this information helps. Thank you for choosing HealthCareMagic. I wish you good health. Best, Dr. Viraj Shah