Do not use if you have migraines. Same neurological fatigue, plus 20 on physical Karnofsky scale. It was well-tolerated with no side effects. Increasing nitric oxide might hurt you in the long run, but if you need to be able to get up to do the dishes, it might help you. Since nitric oxide is implicated in almost every disease, long-term use could be harmful. But so can marshmallows.