The usual cardio exercise routine, some weight lifting, a little calorie deficit, drinking lots of water and making that a lifestyle and switching the type of carbs you eat should guarantee a result of some sort.
I don't recommend any kind of diet plan like Atkins as you will put the weight back on again once you finish the diet. It's a waste of time.
Can you tell us a bit more about yourself? What type of medication are you taking? For how long? How much weight have you gained on it? Are you sure it's the med?
What does your current diet consists of? Approx how many calories/day do you consume? Do you drink a lot of sodas? What is your activity level? How much weight would you like to lose? How long have you been trying to lose it? What have you tried so far? Do you have health issues that would keep you from losing weight - like thyroid, insulin resistance, PCOS, etc?? Do you keep a food diary/journal?
Hmm - sounds like I'm asking for your life history doesn't it? lol. Seriously, we can't really help you without knowing the answers to these questions. Whatever info you can give us will be helpful. Hope to hear from you soon.