Hi. Thanks for asking in Healthcare Magic. Both Kelnor and Zovia contain equal amounts of Ethinodiol diacetate and Ethinyl estradiol. The acceptability of oral contraceptive preparations in various individuals differ from each other. Therapeutically both preparations are found to be equally effective. According to surveys conducted, the order of side effects reported by people using Kelnor 35 is nausea, bloating, anxiety, breast pain and depression whereas for Zovia 35 the order is depression, anxiety, bloating, dizziness and breast pain. Since both are hormonal preparations, these side effects are expected. The symptoms of depression you have, is suggestive of zovia. Although it takes some time for a person to get adjusted to any new preparation of medication when you switch over from one brand to the other, if these symptoms continue or become severe, then you should consult your treating Dr. You can opt for Kelnor again but do not change the pills without consulting your Dr. I hope this is useful to you.