Is it common for ibuprofen to not really help? With physical pain it does nothing for me. It kind of helps with head aches sometimes. I use it maybe a couple times a year, so it's not tolerance.
Ibuprofen is a non-steroidal anti-inflammatory (NSAID). It will reduce inflammation and the associated pain. If your pain is not caused by inflammation then you should talk to a pharmacist about what the best analgesic is for you.
There are several families of painmeds some more harmless than others. Anecdotally I know people that only seem to get relief from ibuprofen, and others that swear only paracetamol (Tylenol) helps, while again others sweat to asperin. Like the other person said.. talk to a pharmacist about options, and see if others work for you.
Some like paracetamol can me taken over the course of a day for multiple days for example post operation.. and they build a level that causes them to work even stronger. But paracetamol can cause lover damage if taken too much.
Like with all drugs, read the darn pamphlet. Opiates are not your friend and should only be taken very sparingly under proper supervision, if at all.. sure they dull pain but are highly addictive.
Source, not a medical professional, so take what I wrote with a grain of salt and consult a professional.
Main benefit for acetaminophen(the American name for paracetamol) is that you can use it on top of an NSAID. That's something you can't do with aspirin. It's good to stagger the dosage for something like a toothache or take both at once for a headache (this is what most OTC migraine medications are, an NSAID[usually aspirin], acetaminophen, and caffeine in one pill).
Can you post a source about acetaminophen building up over time the way you describe? It seems unlikely with such a short half life but I could be wrong.
Try taking it with a dose of acetaminophen. Those two have a synergistic effect that is better than either alone and is often used post surgery for that reason.