Hello, Thanks for posting your query. As you mentioned that you are on birth control pills and taking Kariva for almost 3 years safely and now switched to Viorele. Both drugs are similar in formulation that is Ethinyl estradiol and desogestrel, so both drugs have same effects and risks. However, not every women experience side effects but less than 5% of women taking these pills has experienced weight gain,weakness,stomach pain,depression,breast tenderness, nausea and vomiting etc Every drug has side effects but things you have to care about while taking these pills are avoid smoking and do not take it if you have hypertension,heart disease, bloo-clotting disoders,unusual vaginal bleeding, sever migraine and depression. Seek doctor s advise while taking another drug along with birth control pills. Hope it helps. Take Care!