Multivitamins in large quantities may pose a risk of an acute overdose due to the toxicity of some components, principally iron. However, in contrast to iron tablets, which can be lethal to children, toxicity from overdoses of multivitamins are very rare. There appears to be little risk to supplement users of experiencing acute side effects due to excessive intakes of micronutrients. There also are strict limits on the retinol content for vitamin A during pregnancies that are specifically addressed by prenatal formulas.