Prompted by that study, leaders of an earlier one that tested a different niacin drug, Niaspan, re-examined side effects among their 3,414 participants and detailed them in a letter in the medical journal.
Besides more gastrointestinal, blood-sugar and other complications, the new report details a higher rate of infections and a trend toward higher rates of serious bleeding.
The consistency of the results on studies testing multiple types of niacin "leaves little doubt that this drug provides little if any benefits and imposes serious side effects," said Yale University cardiologist Dr. Harlan Krumholz.
"It's an astonishing reversal of fortune" for niacin, one of the very earliest cholesterol treatments, he said. "This is a billion-dollar drug and it never really had the evidence to warrant that sort of blockbuster status."
The studies were on prescription niacin; risks and benefits of over-the-counter forms are unclear.
Lloyd-Jones said niacin still may be appropriate for some people with very high heart risks who cannot take statins, and for people with very high triglycerides that can't be controlled through other means.
Krumholz said patients should talk with doctors about other treatment options besides niacin.
"This drug can hurt you," he said.
Niacin study: http://www.nejm.org/doi/full/10.1056/NEJMe1406410
Cholesterol guidelines: http://bit.ly/1j2hDpH
Cholesterol info: http://tinyurl.com/2dtc5vy
Heart facts: http://circ.ahajournals.org/content/127/1/
Marilynn Marchione can be followed at http://twitter.com/MMarchioneAP