There are some great natural diuretics that you can try before heading to the pharmacy. I find that vegetables like cucumbers, cabbage, carrots, lettuce, tomatoes, and eggplant can be really great for when you are feeling puffy. The added fiber in your diet also makes heading to the bathroom much easier which can help you feel less bloated.
In addition to food additions, I also drink green tea to help reduce water retention. I find it soothing and it tastes great.
Cranberry juice is also pretty famous for being a natural diuretic. Though, if you are trying to avoid extra calories, I would choose an unsweetened version.