Choosing the Right Parenthetical Punctuation
(Commas, Dashes, or Parentheses)

by Craig Shrives
The Quick Answer
A parenthesis is additional information added into a sentence as an explanation or an afterthought. A parenthesis can be shown using two parentheses (brackets ), two commas, or two dashes. The choice is yours. Here are some guidelines:
  • Using Dashes. Your parenthesis will be easily seen, but dashes can look a little stark.
  • Using Commas. Commas make for a normal-looking sentence, but commas can be confused with other commas in the sentence.
  • Using Parentheses (Brackets): Your parenthesis will be easily seen, but brackets can make official correspondence look a little unorganized.
choosing commas, dashes, or parentheses (brackets)

Use Commas, Dashes or Parentheses (Brackets) to Show a Parenthesis

A parenthesis is additional information added into a sentence as an explanation or an afterthought. For example (parenthesis shaded):
  • John, a 7-year-old cat from Doncaster, hid in the engine area of his owner's car for a 60-mile trip to the seaside.
  • Peter, I've heard it said, used to be a drag queen before he took up body building.
When a parenthesis is completely removed, the sentence is still grammatically correct. A parenthesis can be separated from the rest of the sentence by commas, dashes, or parentheses (brackets) (all called parenthetical punctuation).

It is your choice which parenthetical punctuation you use. It is normal to use commas, but they can be easily confused with other commas in the sentence. Parentheses (brackets) make your parenthesis easily identifiable, but they can look a little informal. To make your parenthesis really stand out, you can use dashes, but they can look a little stark.

Examples of Parenthetical Punctuation

Here are some examples with commas, dashes, and parentheses used as parenthetical punctuation to mark a parenthesis. (NB: Try reading each example with the parenthesis removed. It will still make sense.)
  • Jamie Buxton, who fainted in church during his wedding, apologized to his wife by booking two tickets to New York.
  • (The parentheses chosen by the writer were commas. However, parentheses or dashes could equally have been used.)
  • At midnight last night, Skip (a guard dog for Bonds Ltd in Bury) hospitalized two burglars before returning to eat the steaks they had thrown him.
  • (The writer chose parentheses because there was already a comma in the sentence.)
  • Dave Jenkins' best friend, Adam Wright-Smith, stabbed him through the heart while testing a knife-proof jacket. Dave is expected to make a full recovery.
  • (The writer chose commas, possibly because there were already two hyphens in the sentence, and dashes look similar to hyphens.)
  • This week, Mark Jones — who has lived in our village for 20 years — became, for the first time, the world Scrabble champion and, for the third time, the national Cluedo champion.
  • (The writer chose dashes for the first parenthesis to make it stand out and because there were lots of commas in the sentence.)

Terms Like "However" and "As a Result"

When they appear mid-sentence, comments such as "however," "therefore," "as a result," "as far as I am concerned," "for all intents and purposes," and "subsequently," "so to speak," fall into the category of parenthesis too. (As a rule, parentheses are not used with these.) For example:
  • The slow cooker I purchased at your store is, for all intents and purposes, utterly useless.
  • Darius, on the other hand, writes his own songs.
  • On a happier note, her latest song — Wind Me Up Baby — is , according to those in the know, expected to enter the charts in the top 5.
  • ("Wind Me Up Baby" is a parenthesis, and so is "according to those in the know." Try reading the sentence with them removed. It still makes sense.)
  • It rained all day, and, as a result, the hut collapsed.
  • (It is not uncommon for a conjunction (here, "and") to be preceded by a comma and followed by a comma. The first comma is required because the "and" starts an independent clause (i.e., it has nothing to do with the parenthesis). The second comma is required because it is the start of the parenthesis "as a result." Many writers feel uncomfortable with surrounding a word like "and" with commas, and they omit one. The commas are correct. Be confident. Leave them all in.)
  • It rained all day and, as a result, the hut collapsed.
  • It rained all day, and as a result, the hut collapsed.

What Should I Use for Parenthetical Punctuation?

It is your choice whether to use commas, parentheses, or dashes. Here is a summary of the pros and cons:
  • Dashes — parenthesis easily seen, but dashes look a little stark
  • Commas — normal-looking sentence, but commas are often confused with other commas in the sentence
  • Brackets — parenthesis easily seen, but brackets make official letters look a little unorganized

Don't Forget to End the Parenthesis

Always remember to mark the end of the parenthesis. When using commas or dashes, writers often forget to end the parenthesis. This is as wrong as not closing a pair of parentheses.
  • Danny, however had sharp features and greasy hair.
  • (Another comma is needed after "however.")
  • The zander — one of the fastest fish in European waters often school together around the edges of lakes.
  • (Another dash is needed after "waters.")

Parenthesis in Apposition

The term "in apposition" just means "the same." When a parenthesis is the same thing as whatever it follows, it is called parenthesis in apposition.
  • Kent Oliver — the only professional jockey from Jersey — won his first race on Tuesday.
  • (Kent Oliver is the professional jockey. This is parenthesis in apposition.)
  • At midnight last night, Skip (a guard dog for Bonds Ltd in Bury) hospitalized two intruders who broke into the company yard.
  • (Skip is the guard dog. This is parenthesis in apposition.)
  • Jamie Buxton, who fainted in church during his wedding, apologized to his wife.
  • (This is not parenthesis in apposition.)
Interactive Exercise
Here are three randomly selected questions from a larger exercise, which can be edited, printed to create an exercise worksheet, or sent via email to friends or students.

See Also

Commas before conjunctions (e.g., and, but, or) Using commas for parenthesis What is parenthesis in apposition? Using dashes A useful list of lessons on punctuation