There is no recommended time of day to take niacin supplements, according to WebMD. However, if niacin causes an upset stomach, WebMD recommends taking it with food. Some health care providers also recommend taking it along with aspirin, an antihistamine or a nonsteroidal anti-inflammatory drug to minimize flushing.
Strong evidence suggests that niacin is effective when used as a treatment for high cholesterol, reports WebMD. It raises HDL, or good, cholesterol while lowering triglycerides as effectively as some prescription-only medications. However, the high doses needed to make it an effective treatment for high cholesterol pose risks such as gastrointestinal problems or liver damage.