Writing without em-dashes: a three-month experiment

In December I ran a grep on my last fifty LLM-generated drafts. One punctuation mark showed up in 49 of them.

It was the em-dash.

The tell

The em-dash is a versatile tool. It can signal a mid-sentence amplification, inject a parenthetical thought, or set off a list. It creates a specific rhythm, a pause longer than a comma but more integrated than a period. It is the punctuation of the confident aside.

Large language models love it. They are trained on a vast corpus of published text, much of it from magazines and online journals where this "house style" is common. The em-dash allows a model to connect two related but distinct ideas without committing to a stronger logical connector like "because" or "therefore". It is a syntactic hedge. It lets the model bolt on a clause that feels important without having to fully integrate it into the grammatical structure of the main sentence.

The result is prose that feels breathless and slightly unfocused. It is a string of qualifications and additions.

Consider this common pattern:

• With em-dash: The system architecture is complex—requiring a deep understanding of microservices and event-driven patterns.
• With comma: The system architecture is complex, requiring a deep understanding of microservices and event-driven patterns.
• With period: The system architecture is complex. It requires a deep understanding of microservices and event-driven patterns.

The em-dash version is not wrong. It is just lazy. It fuses two complete thoughts into one. The comma version is grammatically weaker, creating a comma splice in some contexts. The period version is clear. It is direct. It forces two separate statements to stand on their own.

Another example:

• With em-dash: We need to refactor the authentication module—the one nobody has touched since 2022—before we can proceed.
• With comma: We need to refactor the authentication module, the one nobody has touched since 2022, before we can proceed.
• With period: We need to refactor the authentication module before we can proceed. It is the one nobody has touched since 2022.

Here, the em-dash injects a parenthetical. It works, but it also interrupts the primary action of the sentence. The period forces the writer to decide what is more important: the action or the historical context.

One more for lists:

• With em-dash: The deployment failed for three reasons—a timeout on the database migration, an expired SSL certificate, and a missing environment variable.
• With colon: The deployment failed for three reasons: a timeout on the database migration, an expired SSL certificate, and a missing environment variable.
• With periods: The deployment failed for three reasons. The database migration timed out. The SSL certificate was expired. An environment variable was missing.

The colon is the formally correct choice here. The em-dash is a stylistic flourish that has become a default for LLMs.

The constraint

In January 2026 I banned the em-dash from everything I write. This includes articles, emails, technical documentation, and even personal notes.

The rules were simple. No em-dashes (—). No en-dashes (–) used as a substitute. No double-hyphens (--) as a stand-in. My only tools for creating a hard pause or introducing a clause were the period and the colon.

The point was not to be a punctuation purist. The point was to remove my crutch. It was also the LLM's crutch. By taking it away, I wanted to see what would happen to my own writing and my editing process.

What broke first

My transition sentences. I quickly discovered that about 80% of my sentences meant to bridge two paragraphs relied on a mid-clause aside. I would state a topic, use an em-dash to inject a clarifying or contrasting thought, and then finish the sentence. It was a cheap way to add nuance.

Without the dash, I was forced to break these complex thoughts into smaller, more declarative units. The result was an immediate change in my prose. It got punchier. Sentences became shorter and more direct.

It also got ruder. There is a politeness to the em-dash. It softens a declaration by attaching a rationale within the same breath. A period is a full stop. It is an assertion that stands alone, without apology or immediate qualification. I found my writing became more confident and, at times, more abrupt. I consider this a good tradeoff.

What got better

Readability. Readers do not read every word. They scan. Their eyes jump from the beginning of a sentence to the end. A period provides a definitive resting point. A screen full of short, period-terminated sentences is less intimidating and easier to parse than a dense block of multi-clause sentences held together by dashes.

The constraint also supercharged my LLM output audits. I often use models like Claude or Gemini to generate a first draft from an outline. My editing process now includes a simple, brutal first pass: search for em-dashes.

Any draft I get back that contains an em-dash is immediately suspect. It goes back for a rewrite with a prompt to "use only periods and colons to separate independent clauses". More importantly, it is a signal that the model has likely produced other, more subtle forms of lazy syntax. The rule caught 12 instances of "helpful" em-dash injections in post-mortem drafts I had already edited. The model was putting my crutch back in my hand.

Here is the command I run on my content directory:

# Recursively search all mdx files for the em-dash character
# and print the filenames and line counts.
grep -c '—' content/**/*.mdx

If the output is anything other than zero for a new file, I know I have more work to do.

What I miss

Lists. A colon is the correct tool for introducing a list, but the em-dash can feel more natural for setting off a list at the end of a sentence. It has a certain narrative flair. I use a colon now. It works. It just feels more formal, less conversational.

Parentheticals are still a part of my writing. I just use parentheses now. They are visually distinct and clearly signal to the reader that the enclosed text is an aside, a non-essential piece of information. This is their job, and they do it well.

The meta-lesson

You cannot detect LLM prose by em-dashes alone in 2026. The models are too good, and the tells are becoming more subtle. But that was never the point.

The point is that a personal constraint forces attention. By forbidding one specific punctuation mark, I was forced to think more deeply about every single sentence I wrote and edited. How are these two clauses related? Should they be one thought or two? What is the most important piece of information here? Does this aside add value or just clutter?

That level of attention is what separates human editing from a human pretending to edit. It is the difference between wrestling with the structure of a thought and simply polishing the words an AI has already arranged for you. The constraint is a focusing mechanism for that attention.

Exceptions

The rule has a few obvious exceptions.

1. Code. A minus sign or hyphen in a code block is not an em-dash.
2. Direct quotes. If I am quoting someone else's text, I reproduce their punctuation exactly. I do not "fix" their em-dashes.
3. This post's title. The title uses a colon, not an em-dash. That was a deliberate choice to be consistent with the post's own thesis.

The work

The em-dash was never the problem. My laziness was. The rule is a bandage. The habit is the work.