International unit

This article is about the pharmacological unit. Not to be confused with International System of Electrical and Magnetic Units, International System of Units, or international unit of enzyme activity.
Multivitamins nutrition facts label showing that the international unit of, for example, vitamins D and E correspond to different gram values

In pharmacology, the international unit (IU) is a unit of measurement for the effect or biological activity of a substance, for the purpose of easier comparison across similar forms of substances. International units are used to quantify vitamins and biologics (hormones, some medications, vaccines, blood products and similar biologically active substances).

International units as used in pharmacology are not part of the International System of Units (SI).[1]

  1. ^ Cite error: The named reference OED was invoked but never defined (see the help page).