As long as it’s comfortable then it isn’t harmful. It often depends on your chest size. Source: my wife is a runner.
Running
A place for runners.
Yeah, I think this is the most important point to touch on. The answer to this question will vary wildly depending on your bust size.
I don’t think you’d have any long term issues if it’s comfortable for you (of course, depending on size). I personally like to run in nursing bras. They offer support without being too tight or restrictive and they’re easier to get on and off. But if no bra is working for you then I think you should be okay with running that way.
Oh, nursing bras! That's an interesting idea. I might try that!
I welcome the support, but I just need to find something that isn't so tight around my chest, because it makes it harder for me to just enjoy running
I'm so jealous. Chaffing and bouncing is often too much for me.
Do whatever makes you most comfortable!