All LuLu's Lashes eyeliner ingredients are commonly found in most popular makeup and skincare products. The main ingredient that makes it work is iron oxide. Princeton Consumer Research independently studied the effects of prolonged magnetic lash use in healthy female subjects. Not a single adverse reaction was found. Having magnetic and iron content near your eyes produces no long term negative side effects. For those with pre-existing eye conditions, we do not recommend any eye products, including LuLu's Lashes.