Hello Femilon is an oral contraceptive pill , it contains a combination ( desogestrel+ethinylestradiol ) of hormones that help prevent pregnancy . After delivery due to dietary habit , usually most of female gain weight , so same is in your case . If you want decrease weight avoid spicy , fried, oily foods, also avoid pizza, burger sweets , do regular exercise . As far as concerned about the side effects of this drug , these are : Intermenstrual bleeding, post-medication amenorrhoea, changes in cervical secretion, aggravation of endometrium secretions and vaginal infections. Nausea, vomiting, mood changes, depression , CHANGES IN WEIGHT , fluid retention. These are rare side effects and usually females can tolerate easily and the drug adjust after some cycles . But for weight gain , you should do as mentioned above. Otherwise drug is safe.