Oxford Comma
Comma on the Couch
  • Punctuation is important for clarity.
  • Clarity is especially important for academic manuscripts.
  • Use the Oxford comma to increase the clarity of your science manuscript.


Proper punctuation is critical for clarity, as made very clear in the very popular book, Eats, Shoots & Leaves by Lynne Truss. In this humorous book about proper punctuation, Truss cleverly demonstrates why commas are important to clarity. The giant panda eats shoots and leaves. That is, its diet comprises bamboo shoots and leaves. Improper addition of commas, however, changes the meaning of this sentence entirely, making the panda seem to be dangerous. In the following sentence, "The panda eats, shoots, and leaves.", the panda is understood to eat its meal, take aim with an arrow or weapon, and then exit the scene.

In English language editing of science manuscripts, punctuation is especially important for both clarity and conciseness. Proper punctuation can help you convey the take home message of your manuscript, while at the same time improper punctuation can lead to complete confusion. Use of the Oxford comma, also known as a serial comma, is generally considered optional, but science manuscripts are often characterized by long and complex sentences, and the Oxford comma is critical for clarity. The Oxford comma is placed right before the coordinating conjunction (and, or, or nor) in a list of items. Let’s look at the following sentence.

Duloxetine and citalopram may be prescribed for postpartum depression. We investigated the effects of these antidepressants, alcohol and barbiturates in an animal model of postpartum depression.

Now, a new mom who is fraught with anxiety and sleeplessness may be tempted to drink alcohol or take barbiturates, but these substances are certainly not known for their antidepressant effects. Without the Oxford Comma, it seems that the authors of this study are evaluating these substances for their antidepressant effects. The simple addition of the Oxford comma clarifies this sentence: Four different drugs are being investigated for their effects on postpartum depression: the antidepressants duloxetine and citalopram, alcohol, and barbiturates. The Oxford comma removes the ambiguity. The Oxford Comma allows you to be concise while keeping your meaning clear. On the other hand, knowing when not to use the Oxford comma is just as important as knowing when to use it. Consider the following example:

The effects of NMDA antagonists, MK-801 and DxM were evaluated in a model of chronic pain.

In this case, inserting a comma would be confusing because the NMDA antagonists being referred to are, in fact, MK-801 and DxM. In this case, only two drugs are being studied.

The Oxford comma, therefore, removes ambiguity by offering a distinction between different things. The Oxford Comma keeps your meaning clear and your writing concise.