TeaForum.org

How does loose leaf tea compare to little bags if cold brew tea was to be made?

This question is so vast in scope the only real way to answer it is to say “try it yourself”.

But might it still cause gastric problems in some people?

It could even cause hallucinations.

(To be serious, though, your question is indeed very broad: what tea? what temperature? what ratio of tea leaves to water? etc etc etc. The answer that fits best is "it depends," sadly.)