Best way of safely outputting user submitted content

[eluser]jakub[/eluser]
Today I found myself trying to think, what if for some reason my code is sql injected and a comment or a user post starts loading javascript or does something else.

I want to be able to sanitize output. Appart from my input security, is there something I should consider like:

Code:

sanitize_output($post['comment']);

or does CI handle this for me? I'm stripping things like common tags, but I'm concerned what if someone uses Cyrillic or alphabet to inject something.

Guess I'm looking for best case of outputting user content, I'm already securing the input/submit, I want to make sure the output is handled as well.

Thanks!