I've seen it mentioned many times. I have never used it but you want to be sure red thread is mentioned on the label. It seems to be a little different from other fungal diseases.

Where do you live?
What kind of grass do you have?

I live in upper east Tennessee and I have 100% bluegrass. it says on the bag it is good for all fungi, including red thread.

It only has 2 ++ on the chart, I don't think is going to help you much if all. Your lawn will eventually grow out of it.

Click on the link below for more info:

It is under the name of Eagle.

Here is a link that might be useful: Red Thread Fungal Disease