In the metric system, a microgram (μg or sometimes ug) is 1/1,000,000 of a gram (1 × 10–6), or 1/1000 of a milligram, is one of the smallest units of weight/mass commonly used. The abbreviation μg is often used in scientific literature, but JCAHO recommends that hospitals do not use this abbreviation in handwritten orders due to the risk that the Greek letter μ could be mistaken for an m, resulting in a thousandfold overdose. The abbreviation mcg is recommended instead.1
