Brackets/parentheses

UK English: use round brackets throughout for nested brackets.

US English: use round brackets followed by square brackets for nested brackets.

UK English: The standardized mean difference was -0.02 (95% confidence interval (CI) -0.13 to 0.08).

US English: The standardized mean difference was -0.02 (95% confidence interval [CI] -0.13 to 0.08).

Square brackets may be used in chemical formulae, mathematical formulae, edits to quotations, or to indicate an error in the original version of quotation.

pH = -log₁₀ [H⁺]

… as Jones said, "there are very few people who are resistant to [morphine]." (where morphine replaces 'this medication' to ensure contextual accuracy)

Smith says "students tend to overlook there [sic] health".

Colon

Follow a colon with a lower-case letter unless the following word has to start with an upper-case letter, specifically, a proper noun or an acronym. 

Review topic: cancer

Review topic: HIV/AIDS

Location: London

Location: local hospital

Comma

Use of a comma before ‘and’ and ‘or’ in lists is optional, but be consistent.

I have read Cochrane Reviews about malaria, tuberculosis, and vaccines.

I have read Cochrane Reviews about malaria, tuberculosis and vaccines.

Use commas before ‘and’, ‘or’, and ‘but’ in two-phrase sentences (when these words join the two main clauses).

The reviews are written here, but they are available internationally.

The reviews are sent here by post, or they are sent here electronically.

Dash

There should be one space either side of a dash.

The reviews are sent here by post – or electronically – and then processed.

Full stop

Use one space (not two) after the full stop.

Note: when the publishers format Cochrane reviews, one space is allocated after each full stop. This means if you use two spaces, they will be reduced to one.

Hyphen

Hyphens are used to link word compounds with two or more words used as adjectives, such as ‘six-week interval’ and ‘four-dose regimen’. Be aware that hyphens can sometimes change the meaning of a word, such as ‘unionized’ (with a union) and ‘un-ionized’ (without ions).

There was a six-week interval between doses.

Period

See full stop advice above.

Quotation marks

Use double quotation marks for quoting dialogue and when quoting text from a written source. No other formatting is required for quotations (do not use italics).

In the study “12 participants experienced adverse effects” (Goodwin 1998).

Use single quotation marks in all other instances.

The ‘standard’ approach is to count only major events.