APA has specific guidelines for the use of italics. You can find them in APA 7, Section 6.22. As a general rule, use italics sparingly.
According to the manual, italics are appropriate for:
- titles of books, journals and periodicals, webpages, films, and videos
The Publication Manual of the American Psychological Association is…
In the show Friends, Rachel and Ross…
The American Journal of Psychology includes…
- key terms or phrases, often accompanied by a definition
The term zone of proximal development means....
Adolescents labeled high risk should...
- anchors of scale
Scores ranged from 0 (never) to 5 (continuously)
- general/scientific names, species, and varieties
Italics are inappropriate for:
- mere emphasis
- foreign phrases common in English (et al., a posteriori, ex post facto)
- Greek letters (α)
- nonstatistical subscripts to statistical symbols (Fcrit)
- chemical terms (OH, LSD)
- words, phrases, or letters presented as linguistic examples (note that APA 6 recommended italicizing these linguistic examples but APA 7 recommends putting the terms in quotation marks instead)