“Then” vs “and then”

So, you’ve finally gotten your drabble down to 100 words, and you’re about to send it to your editor when spell-check highlights two words of your final sentence:

She dropped the mic, then left.

You hover over, and the corrector wants to change the comma to an and, adding an extra word. Do you have to correct it, or can you leave it?

Leave it. The corrector is technically right, but using a comma + then is so common that it has become a correct option.

In this sentence, you have two independent clauses (complete sentences) that share the same subject (she) joined into a single sentence using a comma and the word then:

Independent clause 1: She dropped the mic.
Independent clause 2: She left.
Resulting sentence: She dropped the mic, then left.

This pattern mimics a common construction used to make prose less repetitive—the compound sentence.

Instead of repeating she at the beginning of both sentences, you can combine them to make a compound sentence. In the first example below, the clauses have the same subject, which allows you to join them using a coordinating conjunction (like for, and, nor, but, or, yet, so, etc.). In the second, the clauses have different subjects, which necessitates a comma before the coordinating conjunction:

Compound Sentence 1: She dropped the mic and then left.
Compound Sentence 2: She dropped the mic, and Remi left.

But our sample sentence is different: She dropped the mic, then left. First, we’re using a comma even though the subjects are the same. Second, then isn’t a conjunction. So technically, we’re attempting to join two clauses using a comma and no conjunction, which is a comma splice.

A comma splice gets its name from splicing together two independent clauses (complete sentences) with a comma. The reason it’s a problem is because the comma creates an expectation that the information to follow will add to the independent clause. When the reader finds a whole new independent clause after the comma, they often have to re-read the sentence to understand it. So, we either replace the comma with a conjunction or use different subjects and add a conjunction after the comma.

Expectation (of restrictive clause): She dropped the mic, which had grown slick with sweat.
Comma splice: She dropped the mic, she left.
Compound sentence: She dropped the mic and left. OR She dropped the mic, and Remi left.

Let’s go back to our original sentence: She dropped the mic, then left. We can see why the corrector is not amused. Even if it were normal to use a comma between two independent clauses with the same subject, then is not a coordinating conjunction.

You may have been told that grammar is a set of rules that writers must follow. While grammar conventions help readers understand what you write, grammar rules actually emerge from how language is commonly used. In other words, the rules change as common use changes.

Historically, our sentence would have been written, She dropped the mic and then left, or even, She dropped the mic; then left. But over time, efficiency and habit seem to have simplified the construction.

More authoritatively, Chapter 6.57 in The Chicago Manual of Style, 17th ed., (the style guide most used for fiction—affectionately referred to as CMOS) describes the use as follows:

The adverb then is often seen between independent clauses as shorthand for and then, preceded by a comma. This usage is perfectly acceptable [ … ] some writers, however, may prefer to use a semicolon, which is strictly correct.

First we went out for shiitake burgers, then we enjoyed vegan sundaes.

or

First we went out for shiitake burgers; then we enjoyed vegan sundaes.

but

First we went out for shiitake burgers, and then we enjoyed vegan sundaes.

By perfectly acceptable, CMOS is saying that it’s your choice whether you follow the old way or the new way. Unfortunately, grammar correctors aren’t as rigorously maintained as CMOS for exceptions to the rules, so you’ll have to contend with the highlighted text if you’d like to keep your word count.