I just successfully defended Redcliffe in Dragon Age Origins as a Mage. I noticed that there is some blue smoke surrounding me, but looking at my 'modifiers' the only thing I can see is 'coughing blood'. Is the blue smoke a glitch or is there something which might cause it?
"Blue smoke" sounds like the spell cleansing aura. Check your mages to see if any of them have it active.
As mentioned in another answer, they likely cast the spell because someone in the party was injured. However, my experience is that only the initial casting of the spell removes injuries, not the persistent "aura" effect which heals hit points. So if you see the aura and are still injured, you need to turn off the aura, wait for the cooldown, then cast it again with your injured party member in range in order for it to remove the injury.
Blue smoke as in you have a spell active? Can you post a screen shot? If you're coughing blood use a injury kit to heal yourself and see if the smoke goes away.
IIRC when you have certain spells active they aren't listed as under the modifiers as that's only for something that is physically affecting you i.e ice enabled, that should list there, but other spells, say spell might iirc won't.
Coughing blood is a modifier caused by an injury so it should not be related to the blue smoke. Apply a heal kit to your party member who has the coughing blood modifier and that should cure it.
It sounds like a Spirit Healer (mage) who is casting cleansing aura, however be aware that Cleansing Aura will not remove an injury on the Spirit Healer themself
While this mode is active, waves of healing and cleansing energy emanate from the caster, restoring health to all nearby allies every few seconds and curing the injuries of allies very close to the caster.
For more information on injuries such as coughing blood, click here