Niacin, also known as nicotinic acid or vitamin B3, has been used intravenously and orally as both a preventative and an abortive treatment for migraine. There have been case reports suggesting niacin's effectiveness published in the medical literature, as well as a handful of small studies. Whether the usefulness of the drug was related to the action of the drug itself or to a placebo effect is unclear. Unfortunately, as of early 2008 there were not yet any well-designed, randomized, controlled trials of niacin as a migraine treatment.

Researchers believe niacin may be effective in stopping a migraine because of its vasodilatory action (it opens blood vessels). This vasodilatory action may also cause side effects such as flushing of the skin, a warm sensation in the face or neck, and fainting or dizziness. Other reported side effects of niacin include itching, dry skin, and nausea. Many of these side effects appear when niacin therapy is first started or when dosage is increased, and then gradually decrease over time.