John Dixon, independent medical writer and trainer in scientific writing skills, provides a useful tip for medical writers who work in MedComms.

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Recorded 09 March 2020. Produced by

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Hi, I’m John Dixon, a trainer in scientific writing, and here’s a bite that I hope may help you with your writing.

Introducing a list with a colon [NEXT SLIDE]

I don’t need to remind most writers that a colon can introduce a list … both run-in and vertical lists.
However … how should we construct the introductory statement before the colon? [NEXT]
Generally, if a colon is used, the introductory statement should form a grammatically complete clause. [NEXT]

So … in this example for a run-in list … They studied three related conditions … colon … asthma, eczema, and hay fever … the introductory statement … They studied three related conditions … forms a grammatically complete clause before the colon [NEXT]

[NEXT] For a vertical list, the same principle can, but doesn’t always apply. We’ll discuss this later. But here … They recommended three investigations … is followed by a correctly used colon [NEXT] … and then a vertical list. [NEXT SLIDE]

For a run-in list, a colon should not break a continuing statement … for instance … separate a verb from its object or a preposition from its complement. [NEXT]
So … it’s incorrect to use a colon in the sentence … They studied asthma, eczema, and hay fever. [NEXT] … [NEXT]
Similarly … It’s incorrect to use a colon in the sentence … The study was limited by poor compliance, intolerable side effects and insufficient recruitment of male participants. [NEXT] … [NEXT]

Adding a phrase such as ‘the following’ tells the reader a list is coming, and a colon can then be used …
… ‘the following’ then becomes the object/complement of the verb/preposition … and then the introductory statement becomes a grammatically complete sentence.
So, taking the first incorrect example above … [NEXT] … this sentence could correctly become … They studied the following … colon … asthma, eczema, and hay fever. [NEXT] … [NEXT SLIDE]

For introducing a vertical list, the situation is a little more controversial regarding the use of a colon if this interrupts what would be continuous statements. [NEXT]

Take this vertical list. The introductory statement … After the meeting, the editorial team agreed that … is not a grammatically complete clause. But each element of the list does run on naturally from the introductory statement and completes a sentence. So … After the meeting, the editorial team agreed that … the readability of the manuscript was excellent … is a complete sentence. [NEXT]

Guides that adhere to the rule of not breaking continuing statements would therefore omit the colon, as illustrated here.
However … [NEXT] some would accept the colon … [NEXT] … [NEXT]

So, as in all good writing and in this case, it’s important to be consistent and follow a style guide. [NEXT SLIDE]

Here are some style guides that I’ve found useful. [NEXT]

Well, I hope that’s helpful. For more bites, visit

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[For the avoidance of doubt: this video is intended to be freely accessible to all. Please feel free to share and use however you like. Cheers Peter Llewellyn, Director NetworkPharma Ltd and Founder of the MedComms Networking Community activity at]