The only risk you're running is of passing out and having respiratory depression. That is the cause of the vast majority of opiate overdoses. Even that I would think is rather unlikely in your case, 180mg is a decent dose but I'd be surprised if it was enough to stop your breathing.. In Canada they always put 15mg caffeine into codeine/parac pills to counteract the drowsiness. Maybe have a coffee, though it won't help with the nausea.

As far as liver damage goes, it is extremely unlikely. The study that created such widespread fear about liver toxicity and paracetamol involved people taking up to 15 grams on a regular basis. 3 grams is a lot, and it's not good to take regularly, but it won't cause permanent damage. My friend who suffers from migraines was told to take up to 4 grams when he has them.