MigreLief supplements do not have any harmful side effects. Potential side effects though rare can be: Riboflavin (Vitamin B-2) can cause urine to become bright yellow. This is normal and harmless. When taking a magnesium supplement for the first time, some individuals may experience loose stools (transient diary) temporarily. If an individual is allergic to any of the ingredients in MigreLief, they should cease taking it. Some individuals can experience gastro-intestinal upset when taking dietary supplements in general Like all...