I've been taking immediate-release niacin for over six years. I've take 2 grams twice day for the most part with no elevation to my liver enzymes (indicative of liver damage). Every time I switch to three times a day dosing (4 grams/day total) I always end up with elevated liver enzymes. For this reason, I would never consider extended- or sustained-release forms.

The flushing effect does get better over time. It also helps to take it after a meal with a glass of water. During the first year, I also took an aspirin 45 minutes before each dose.

I was already exercising quite vigorously when I started and my HDL was 32. Initially I took it to raise my HDL cholesterol and it did raise it to 42. My total cholesterol did drop slightly, as did my triglycerides. I've since learned that focusing on total cholesterol is pointless. At one point my total was 97 and my cardiologist was thrilled.

I've now eat much differently a year and a half later. My total cholesterol is now around 180 and my HDL 70. Earlier this year, I had to discontinue niacin and simvastatin because of elevated liver enzymes. I had changed my diet several months before and I expected my HDL to decrease significantly. I was shocked to see it increase from 42 to 52. My GP asked which med I wanted to start again and I chose niacin. My cardiologist later remarked that he would've put me back on a statin instead.

A complete NMR lipoprotein analysis was performed after being off niacin and simvastatin after 3 weeks. I had a very high LDL particle count and high number of small, dense-LDL particles. A couple of months later on niacin, I ordered another test myself from an online service and was please to see that my LDL particle number was halved and the number of small, dense-LDL particles had decreased by 2/3. My Lp(a) is also very low. Niacin is the most effective agent (besides saturated fat) for increasing HDL, lowering Lp(a) and small, dense-LDL particle count.