Is comma needed if we use "although" in the middle of a sentence?

Solution 1:

When the main clause comes before the subordinate clause, there is normally no comma.

We do use a comma if the subordinate clause is nonessential, which sometimes happens when we use subordinating conjunctions of “concession” (although, though, even though, even if, while, whereas).

If what follows the main clause is nonessential (extra information that can be removed), use a comma. If it is essential (necessary to complete the idea), don’t use a comma. Sometimes it’s a judgement call.

One more note: Although sounds a bit awkward as the head of an essential subordinate clause following a main clause, so a stylistic rule of thumb is to use even though instead of although if the clause is essential.

Essential — surprising — no comma:

She walked home by herself even though she knew that it was dangerous.

Nonessential — extra information — comma:

She walked home by herself, although it was only two blocks.

Here are some more examples:

Essential — surprising — no comma:

I love tangerines even though I hate oranges.
It was cold even though it was July
I said it loudly even though he was standing right in front of me.
I have brown eyes even though my parents have blue eyes.

Nonessential — extra information — comma:

I love tangerines, although I didn’t when I was a kid.
It was cold, although not as cold as yesterday
I said it loudly, although I don’t think he heard me.
I have brown eyes, although they were blue when I was a baby.

_{Further reading: Comma before ‘whereas’, ‘while’, and ‘although’}