Ah, but you see, fire takes away oxygen. Even if fire does not burn, the lack of oxygen would certainly do damage. Even more so if it's [i]liquid[/i] fire- a dragon eats fatty food, and a good portion of the fats are diverted to another belly, where certain chemicals are mixed with it. When mixed with oxygen, it lights up like a christmas tree. A large enough dragon could literally drown someone in it. A large enough dragon could also kill someone with its roar alone, having large enough lungs to tear apart the ears, and farther in.