mcg

[Etymology: microgram] mass North America Particularly for ingredients of consumer pharmaceutical products, alongside the international mg for milligram, a representation of microgram that avoids use of the alien graphic μ; see micro-. (Though improper within the rules of the SI, the prefix for mc could well join the prefix da that replaced the distinct capitalized D for deca- as a practical solution to an inherent problem. The letter u is an alternative.)