I have not used Lasix myself, but I know quite a few who have--almost always with negative experiences.
Here are just a few of the issues with Lasix.
1.) It is non-potassium sparring. In the event of an overdose, this could potentially lead to cardiac arrest, and in terms of appearance, you are more likely to go flat than when using potassium sparring diuretics, as potassium is critical for the maintenance of intracellular water.
2.) It has a long active life, which makes fine tuning more difficult. If you start dropping too much water, there is no way to shut the drug off.
3.) It is too strong. Although increased strength is a good thing with most bodybuilding drugs, it is not so with diuretics. This is because diuretics are non-discriminatory in their effects, pulling water from both under the skin and the muscles. Therefore, the more water you pull out from under the skin, the more water you will lose in the muscles, making them smaller and flatter.
In addition to losing muscular size, the over-use of diuretics also tends to make the individual look watery, which is the exact opposite if what you are trying to achieve. Because the muscles are no longer tight and pushing out against the skin, you lose the thin-skinned appearance associated with being dry, while also losing separation and detail. This is why we see so many bodybuilder looking both small and flat--because they over-did the diuretics. Ideally, you want to dry-out without using diuretics. Doing so will enable you to maintain fullness while maximizing muscular detail.