A run-on is two or more independent clauses jammed together without the grammar that should separate or join them. The most common Brazilian variety is the comma splice (vírgula a mais): two full sentences glued with nothing but a comma. Run-ons are not a sign that the writer can't think clearly — they are usually a sign that the writer is transcribing speech, where clauses really do flow into one another. The fix is not to think differently; it is to add the connective tissue that writing requires and speech does not.
Why Portuguese speech runs on
Spoken Brazilian Portuguese chains clauses with light, repeatable links — above all aí and daí ("and then", "so then"), plus a steady stream of e ("and"). In conversation this is not sloppy; it is the natural rhythm of narration.
Aí eu cheguei, aí ele falou que não ia, aí eu fiquei puto.
So I arrived, and then he said he wasn't coming, and then I got mad. (spoken narration)
Daí a gente saiu, daí começou a chover, daí voltamos correndo.
So then we left, and then it started raining, so then we ran back. (spoken)
This aí... aí... aí pattern is one of the defining features of casual Brazilian storytelling. It is correct and idiomatic in speech. The problem appears when a learner — or a hurried writer — transfers that loose chaining straight onto the page with commas standing in for aí.
Cheguei em casa, estava cansado, fui dormir.
I got home, I was tired, I went to sleep. (comma splice in writing)
Read aloud, this sounds fine — it is exactly how someone would say it. Written down, it is three independent clauses spliced with commas, and formal writing rejects it. The clauses need real connectors or stronger punctuation.
Run-on vs. legitimate comma use
Not every comma between verbs is a splice. A comma is correct when one of the pieces is not an independent clause — for example a list of verbs sharing one subject, or a subordinate clause.
Cheguei em casa, tirei os sapatos e fui dormir.
I got home, took off my shoes, and went to sleep. (a list of actions, one subject — correct)
Como estava cansado, fui dormir cedo.
Since I was tired, I went to bed early. (a subordinate clause before a main clause — correct)
The difference between the splice Estava cansado, fui dormir and the correct Como estava cansado, fui dormir is one word: the subordinator como demotes the first clause so it can no longer stand alone. That is precisely the kind of connective tissue a run-on is missing.
The four fixes
There are exactly four reliable ways to repair a comma splice or run-on. Pick the one that best fits the relationship between the clauses.
1. Add a coordinating conjunction
Insert e (and), mas (but), ou (or), or então (so) — the words that legitimately join two independent clauses. The comma stays before mas; with e the comma is usually dropped.
Cheguei em casa e fui dormir.
I got home and went to sleep.
Cheguei em casa, mas não consegui dormir.
I got home, but I couldn't sleep.
Estava muito cansado, então fui dormir cedo.
I was very tired, so I went to bed early.
2. Subordinate one clause
Turn one independent clause into a dependent one with porque (because), quando (when), como (since), depois que (after), or já que (given that). This shows why or when, not just and then.
Fui dormir porque estava cansado.
I went to sleep because I was tired.
Quando cheguei em casa, fui direto dormir.
When I got home, I went straight to sleep.
Subordination is usually the most informative fix, because it spells out the logical link the comma left implicit. Cheguei em casa, estava cansado hides a cause; Como cheguei cansado em casa, fui dormir makes the cause explicit.
3. Use a semicolon
When two independent clauses are closely related and you want to keep them in one sentence without a conjunction, a semicolon does the job. This is more formal and more literary.
Cheguei em casa exausto; não tive forças nem para jantar.
I got home exhausted; I didn't even have the energy to eat dinner. (formal/literary)
The semicolon signals "these two thoughts are a matched pair" — heavier than a comma, lighter than a full stop. Use it sparingly; overusing it reads as affected.
4. Break into separate sentences
The simplest fix: end one clause with a period and start the next.
Cheguei em casa. Estava exausto. Fui dormir.
I got home. I was exhausted. I went to sleep.
Short, separate sentences can even be a stylistic choice for impact — but as a default repair for a run-on, the period is always available and never wrong.
"Então", "aí", and "daí" in writing
Learners often try to keep the spoken aí/daí in their writing, which looks markedly informal. In neutral or formal writing, replace them:
| Spoken (informal) | Written equivalent |
|---|---|
| aí / daí | então, em seguida, depois, por isso |
| aí ele falou que... | então ele disse que... / em seguida, ele disse que... |
| e... e... e... | vary: e, além disso, depois, por fim |
Cheguei em casa; em seguida, percebi que tinha esquecido as chaves no trabalho.
I got home; then I realized I'd left my keys at work. (written register)
Comparison: how English differs
The comma splice exists in English too, and the rules for fixing it are nearly identical: add a coordinating conjunction, subordinate, use a semicolon, or split. Two Portuguese-specific points matter for English speakers:
- English speakers learning Portuguese sometimes assume that because Portuguese drops subject pronouns, two verbs in a row with a comma must be fine. They are not. Cheguei, estava cansado is still two independent clauses (each verb carries its own subject), so it is still a splice. Dropping the pronoun does not dissolve the clause boundary.
- Portuguese então ("so/then") is a true coordinating link and can join clauses, whereas the spoken aí/daí has no clean written equivalent — there is no single word; you choose from então, em seguida, por isso depending on the logical relationship. English "and then" is more portable into writing than aí is.
Common Mistakes
❌ Cheguei em casa, estava cansado, fui dormir.
Incorrect — three independent clauses spliced with commas.
✅ Cheguei em casa cansado, então fui dormir.
I got home tired, so I went to sleep.
❌ Ele estudou muito, mesmo assim não passou, ficou frustrado.
Incorrect — comma splice chaining three clauses.
✅ Ele estudou muito, mas mesmo assim não passou, o que o deixou frustrado.
He studied hard, but he still didn't pass, which left him frustrated.
❌ Aí eu falei com ela, aí ela concordou, aí marcamos. (in a formal email)
Incorrect — spoken 'aí' chaining in formal writing.
✅ Falei com ela, ela concordou e, em seguida, marcamos.
I spoke with her, she agreed, and then we set a date.
❌ Não gosto dele, ele é arrogante.
Incorrect — two independent clauses with only a comma.
✅ Não gosto dele porque ele é arrogante.
I don't like him because he's arrogant. (subordination makes the cause explicit)
❌ Estava chovendo, decidimos ficar em casa, fizemos pipoca.
Incorrect — three spliced clauses.
✅ Como estava chovendo, decidimos ficar em casa e fizemos pipoca.
Since it was raining, we decided to stay home and made popcorn.
Key Takeaways
- A comma splice is two independent clauses joined by only a comma; the period test reveals it.
- Spoken Brazilian Portuguese chains clauses with aí / daí / e — natural in speech, but not for formal writing.
- Four fixes: coordinating conjunction (e / mas / então), subordination (porque / quando / como), semicolon, or period.
- Subordination is usually the most informative fix because it names the logical link.
- Dropping the subject pronoun does not merge two clauses into one — the splice remains.
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Start learning Portuguese→Related Topics
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- Complex Sentences (Subordination)B1 — A main clause plus one or more dependent clauses — noun, adjective (relative), and adverbial — where the subordinator decides whether the verb is indicative or subjunctive.
- Sentence Combining TechniquesB2 — How skilled Brazilian writers fuse short, choppy sentences into flowing prose — coordination, subordination, relative clauses, gerund/participle reduction, apposition, and nominalization.
- Coordinating ConjunctionsA1 — The five classes of coordinating conjunction in Brazilian Portuguese — additive, adversative, alternative, conclusive, explicative — with comma rules and the key contrast with Spanish.
- SVO Word Order in BRA1 — Brazilian Portuguese is a Subject-Verb-Object language, but a flexible one — adjectives follow nouns, the subject is often dropped, and some verbs put their subject last.