This example will return the HTML the way is it generated by default.

The following code can be used to set the default value of a field.

The built-in striphtml=1 parameter will remove all HTML from that value. But if there are specific tags you would like to leave, you'll need to specify exactly what to allow. Your shortcode for this example will look like [25 leave_html='em,i,b']. You can find more detail on using wp_kses in the codex.