Italic formatting should not be used to add emphasis or make a word or phrase stand out from the text. Your writing should be strong enough to do this on its own. Italics should only be used for longform works, such as books, journals, and websites, and special terms at first use.
The reasoning behind this rule is to ensure strong writing is being developed and used, and to increase readability for your audience. It can be confusing for readers who may mistake incorrectly italicized words as special terms or other types of correctly italicized works.