I am currently taking Codeine and Paracetamol tablets along with Ibuprofen to numb the pain from a tooth ache. The other night I went out for a few drinks with friends but ended up drinking a little more than I should have, especially considering that I was already feeling pretty out of it from the codeine. I have no recalculation of the end of the night but I acted in a way which was completely out of character and I am finding it difficult to understand why I did what I did. I'm not going to go in to details but is this something that could have been caused by the mixture of these drugs? I know now from reading forums that you're not really suppose to mix codeine and alcohol but if you do does it affect your behaviour and judgement?
It can.
Basically the effect of the drugs is magnified. Codeine itself can impair your thinking. Alcohol tends to lower inhibitions.
So, yes. It's possible.
Just to add to Dan's explanation, Codeine affects your thinking because it metabolizes into morphine once you ingest it and most general effect it would have is generating mild euphoria which obviously, when combined with alcohol, that in the end acts as depressant to your central nervous system (the more you drink the more are your mental functions impaired - that's why, for example, your memory gets "blanked"). That's why you slowly lose control, but the danger is not only the morning after you have to face, the more serious threat is that codeine, combined with acetaminophen and alcohol has detrimental effect on your liver. So, please, stay away from alcohol while you take these medications that already are hard for your liver.
basically you drank more alcohol than normal, thats what caused the change