To Period or Not to Period

Periods and italics are often a topic of discussion with my clients. Outside of their use at the end of sentences, traditionally periods have been used to denote abbreviations. Italics have traditionally been used to indicate a foreign language word. However, in recent years, various style guides have started to eschew periods and italics in these contexts.

According to the most recent American Medical Association (AMA) style guide (9th edition, 2007), periods should rarely be used outside of indicating the end of a sentence. For example, periods are not required for Latin abbreviations such as etc, eg, ie, and et al. These words also do not need to be italicised. Roman lettering is perfectly acceptable for foreign words currently in common English usage, including the phrase in vitro.

As well, periods are also not required for acronyms like WHO, HIV, or NCIC. However, remember, the first time an acronym is used in a text it should be expanded. For example, "The World Health Organization (WHO) recently reported...."

On the other hand, periods should be used if you are quoting material from another source that used periods. Periods are also used for the initials in names.

When in doubt, always refer back to the most recent edition AMA style guide.

Source: Iverson C, Christiansen S, Flanagan A, et al. American Medical Association Manual of Style. 10th ed.New York, NY: Oxford University Press, 2007.