As long as you can tolerate paracetamol, it is always much better to take codeine with paracetamol, as alone codeine is only a weak pain killer, but the additional benefit of codeine plus paracetamol is greater than the sum of the two parts (i.e. 2 plus 2 does equal 5 possibly 6). This is still true even if you think paracetamol alone does nothing at all. (Also, paracetamol usually for most people has no side-effects, so it means you can take a lower dose of the codeine, get more pain relief and less of the codeine side-effects). Obviously always make sure you don't take more than the recommened dose of paracetamol - and check you are not on other medication containing paracetamol (it hides in lots of over the counter medicines).
Codeine is a weak opioid and so does have many potential side-effects - not to say you will get them - everyone is different, some people get them all really badly and can't tolerate it, whereas others get hardly any side-effects. (Also pain relief effect is varied - for some people it is wonderful (me) and for other people it does noting).
Most people do get constipated with it, but this is dose dependant, and if only taken when needed, then your bowels can recover on days you don't need to take it. Obviously you may need to increase the normal measures you use when you get constipated (i.e. increase fluid intake, fibre, laxatives etc).
Drowiness is also an issue as well, so if you drive make sure you know the effects fully. I only ever take my codeine at night. If I do need to take it during the day - I don't drive - but these are normally the days I am in that much agony I would never get to work anyway.
When taken for pain it is rarely addictive as in how an addict becomes addicted. However, when used for pain, your body may develop a tolerance and so you need to take higher and higher doses to get the same pain relief. This is usually if you are taking it a few times a day for a few weeks. I normally force myself to have an "opioid" free weekend every now and again and use other pain killers (paracetamol, ibuprofen) just to check that I am not becoming tolerant to it, and also allow my bowels to clear (sorry if TMI).
So this is half my Pharmacist opinion, and half my own experience, as a combination of paracetamol and codiene is what I have worked out is my best pain killer regimen. (plus ibuprofen when active inflammation)
Benign Joint Familial Hypermobility Syndrome (BJFHS) - Confirmed Prof Bird April 2008
I am a Pharmacist and I will give my opinion on these boards. However, always ask your own health professionals for your individual circumstance.