What are the pros and cons of taking niacin?

Pros: May lower your triglycerides and/or raise your HDL. Cons: side effects including flossing/heat sensation. Limited to no data on improving outcomes. (may make your labs look better on paper, but not reduce your risk on MI or stroke)
Niacin. Supplementing with 2000-3000mg of flush free Niacin daily can help to control your cholesterol levels quite nicely, even increasing your HDL and converting your LDL to a less harmful subtype. As a negative, Niacin can cause facial flushing and redness so get the flush free variety. And have your liver enzyme values monitored, as they can be affected by Niacin use.