Complain about and complain of

I saw some examples of complain from a dictionary as below.
I don’t quite understand what the difference between complain about and complain of.
They are not interchangeable?

complain about
She often complained about not feeling appreciated at work.
Several customers complained about the service they received.
complain of
Several women have complained of sexual harassment.

There really isnt much difference. The only thing I can think of is that complain “about” puts slightly more emphasis on what is being complained about and complained “of” puts slightly more emphasis on the complaining.


I would say “complain about” is better in all three of the examples you give.
“complain of” is often used when talking about an illness: She complained of a headache.
“complain about” suggests that the person actively complained to a responsible person about an injustice.


In the examples that you present COMPLAINED OF is interchangeable with COMPLAINED OF. I cannot think of an instance in which they are not interchangeable.