How to use Flonase Spray, Suspension. If you are using the over-the-counter product to self-treat, read and follow all directions on the product package before using this medication. Flonase and Weight Gain Weight gain is a side effect that healthcare providers have seen in people taking Flonase. Weight gain was reported in postmarketing experience with the drug, however, which means that it was not actually seen during clinical trials. Flonase is the brand name for fluticasone nasal spray, a prescription drug used to prevent and reduce nasal inflammation. Doctors prescribe Flonase to treat symptoms of seasonal and year-round. Summary. Weight loss is found among people who take Flonase, especially for people who are female, 40-49 old , have been taking the drug for 5 - 10 years, also take medication Neurontin, and have Pain. 3 days ago I began feeling a loss of appetite and discontinued use of the flonase as I suspect that the double dosing may be causing my stomach upset and loss of appetite. I am aware that prednisone pills can make me put on weight and make my face puffy. So, since Flonase contains a steroid, will it cause weight gain if used on a regular basis for allergies and my ENT wants me to use it since I have loud ringing in my ears also. 3 days ago I began feeling a loss of appetite and discontinued use of the flonase as I suspect that the double dosing may be causing my stomach upset and loss of appetite. Flonase rocks! I am already a fatty and because I cut out soda recently expected a weight loss.I could double in size and I would not stop using this product! The information reflected here is dependent upon the correct functioning of our algorithm. From time-to-time, our system might experience bugs or glitches that affect the accuracy or correct application of mathematical algorithms.