Hi, Lo Loestrin Fe contains both ethinyl estradiol and norethindrone which is used to prevent pregnancy with the lowest dose of estrogen possible that may reduce side effects, especially in perimenopausal women. Side effects of Lo Loestrin Fe are nausea, vomiting, headache, bleeding irregularities, breast tenderness, spotting or bleeding between periods, chest tightness, chest pain, breathing difficulties, rapid heartbeat, dizziness, fatigue, weakness, stomach cramps, acnes, changes in weight, unusual tiredness, absent, missed, heavy or lighter menstrual cycles, allergic reactions etc. If these side effects persist or bother you, then you should consult your doctor. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Zubayer Alam, General And Family Physician