In some cases doctors prescribe two or more drugs at a time. This is called combination therapy. Resins or plant fibers and the new margarines are sometimes given with statins, and their addition can produce a further decrease in LDL cholesterol levels of 20 to 25 percent. The further addition of niacin can produce yet another 15 to 20 percent decrease. The sum of these three types of drugs may result in a decrease in LDL cholesterol levels of up to 70 percent. But you should remember that each drug has its own possible array of side effects and these are now all added together. You should be carefully monitored by your health professional for any such adverse effects from the combination of these powerful drugs.