Large doses of this B vitamin are the most effective therapy for raising HDL cholesterol levels. Niacin can also lower triglyceride and LDL cholesterol levels but frequently causes adverse effects, especially when dosages higher than 2 grams a day are taken. Although niacin is available over the counter, all preparations should be used under a doctor's supervision.

Skin flushing and itching are common but not dangerous. Extended-release niacin (Niaspan) causes less flushing than immediate-release niacin (Niacor) and has the added advantage of once-daily dosing at bedtime, rather than three times a day with meals.

For more on side effects, see Lipid-Lowering Drugs (PDF).