hI Deljo -
Why are you only taking 20 mg of Lasix when your prescription calls for 40 mg?
Like you, I start with 1/2 dose of the prescription prescribed - except for antibiotics - but, when that isn't enough, I increase it until I have reached the dosage prescribed. I believe that we know our own body's reaction to drugs; however, since our doctors know so very much more than we do about our needs, we must follow their directions. Therefore, since the 20 mg. didn't lower your edema, you really should take the full dosage of 40 mg. before you tell your doctor that the drug didn't work.
I also have swelling of legs during the day, which goes down by morning. I do not have diabetes (yet), but I have been trying out different beta blockers for high blood pressure, and one (Norvasc) caused my ankles and legs to swell much more even when I hadn't been on my feet for long periods of time. Since changing to another drug, I have noticed that the swelling is minimal.
My situation is different, I think. Lasix is a rather strong diuretic, but it certainly does the trick when taken as prescribed; and it won't harm you.
I know many people who take Lasix; they give it intravenously in hospitals.
I hope you'll take your prescribed dosage! You might see a huge difference in the swelling. Good luck!