Why is diuretic working like this?

[grannyheart]

Has had edema in feet and ankles for about 18 months...dr just said from the lungs....prescribed daily lasix of 20mg but take more if needed.  The lasix never seemed to do much.....and if it reduced it we hardly noticed that much of a difference.  He got to a point of not taking it and discovered that when he didn't take it the edema seemed to go down quite a bit.  Then he'd get nervous about not taking it and would start it up again and the edema came back quite a bit. Dr just says to keep taking it and up it if necessary.........is there any logic to this noticeable difference in when taking it and or not taking it.............for FYI. after staying off of lasix for a number of days when we notice less edema it does start to build up a little and that is when he starts taking it again and then the edema comes back full blown...
Any thoughts would be appreciated!!

[Sandra Y, RPh]

Lasix is usually the drug of choice for edema. I am not sure why it is not working or why the edema gets worse when taking it. It could be a very sensitive sulfa allergy and your body rejects the drug and that is causing a problem.

[grannyheart]

Calling the doctor tomorrow to check out the possibilty of a allergic reaction to lasix...but now also considering the edema may not be from the heart ...I think it is non-pitting edema from what I've observed....if that makes a difference.........