Microgram, mcg

[sarawilcox]

Our current style guide entry says:

microgram
Write "microgram" in full. Do not shorten it to "mcg".

It helps to explain that a microgram is 1,000 times smaller than a milligram (mg).

We only use the microgram symbol (μg) if people will find it helpful, for example, if they will see it on their medicines or vitamins packet. In cases like these, we add the following when we first mention micrograms: "The word microgram is sometimes written with the Greek symbol μ followed by the letter g (μg)." We explain that it's a Greek symbol so that people who use screen readers understand it when they hear an unexpected sound.

We do not use μg as an abbreviation in text that follows.

We've had feedback from a user to ask if we can add mcg because "I couldn't work out what the labels on the containers meant".

GOV guidance on labelling meds and the EU Meds Agency guidelines both say to spell out "micrograms" in full, unless it cannot be accommodated, e.g. on a small label, in which case to use mcg, not μg. This is because there've been a number of errors where people have misunderstood the abbreviations and taken the wrong dose.

Most bottles seem to be labelled in μg but some say mcg.

Colleagues suggested adding mcg in brackets after the term "micrograms" in full. NHS.UK clinicians agreed. (In other words, only where we spell out micrograms first.)

Our guidance does say that we can use μg, even though GOV and the EU say not to. We say: "only use the microgram symbol (μg) if people will find it helpful, for example, if they will see it on their medicines or vitamins packet. In cases like these, we add the following when we first mention micrograms: "The word microgram is sometimes written with the Greek symbol μ followed by the letter g (μg)."

[sarawilcox]

At July Style Council meeting, we agreed to change our guidance on microgram slightly as follows. To be agreed with our clinical team before publishing.

We've removed the word "Greek" before "symbol" but there's an action on Sara to check if we can/should include it in hidden text for screen reader users.

[sarawilcox]

To be published 19 September. Approved by clinical team.