(European here as well, so I'm referring to way lower dosages compared for example to the US) I don't have any 100% proof of it being caused by painkillers, ho

(European here as well, so I'm referring to way lower dosages compared for example to the US) I don't have any 100% proof of it being caused by painkillers, however years ago I took Ibuprofen based painkillers on unusual higher dosage for some time to fight against pretty nasty back pains (driving exclusively bikes for 38 years comes at a price). After some time I developed some strong anemia, which scared me a lot for having a bad family history (some cancer cases, and my father died of leukemia); by my doctor's advice I did repeated blood tests and stopped taking painkillers for a while (and later never get again to that dosage) while starting a cure with iron and folate. Red blood cells took a while to fully recover but ultimately they did. About backpains, I later learned with immense relief that in many cases postural training will lead to results that painkiller can only dream of: I still have my back problems, and after a motorcycle accident also a stabilized column with screws et al, but no need for painkillers: I keep them for headaches or other things, but my back has never been so damaged and so pain free (touches various things...:).