| Microgram | |
|---|---|
 Anutrition facts label displaying, for example, the amount offolic acid in micrograms | |
| General information | |
| Unit system | SI |
| Unit of | mass |
| Symbol | μg |
In themetric system, amicrogram ormicrogramme is aunit ofmass equal to one millionth (1×10−6) of agram. The unit symbol isμg according to theInternational System of Units (SI); the recommended symbol in the United States and United Kingdom when communicating medical information ismcg. In μg, the prefix symbol formicro- is the Greek letterμ (mu).
When the Greek lowercase "μ" (mu) is typographically unavailable, it is occasionally – although not properly[citation needed] – replaced by the Latin lowercase "u".
The United States–basedInstitute for Safe Medication Practices (ISMP) and the U.S.Food and Drug Administration (FDA) recommend that the symbol μg should not be used when communicating medical information due to the risk that the prefixμ (micro-) might be misread as the prefixm (milli-), resulting in a thousandfold overdose. The ISMP recommends the non-SI symbolmcg instead.[1] However, the abbreviation mcg is also the symbol for an obsoletecentimetre–gram–second system of units unit of measure known as millicentigram, which is equal to 10 μg.
Gamma (symbol:γ) is a deprecated non-SI unit ofmass equal to 1 μg.[2]
Afullwidth version of the "microgram" symbol is encoded byUnicode at code pointU+338D ㎍SQUARE MU G for use inCJK contexts.[3] In other contexts, a sequence of the Greek lettermu (U+03BC) and Latin letter g (U+0067) should be used.
