I often take painkillers (acetaminophen aka paracetamol), but I’ve noticed that it’s much more effective if I take them TOGETHER with my ADHD medication (ritalin aka methylphenidate) + my morning coffee. If I don’t take them AT the same time, the painkiller is far less effective.
I do not exceed the maximum dosage of painkiller (1gram per intake, mornings), but alone this would barely suffice to kill my morning headache.
My hypothesis is that since the LIVER has to convert all three, I am effectively overdosing on either substance (painkiller or ADHD meds), and damaging my liver in the process.
In the US, you can get varying dosages based on a variety of commercial factors.
That being said, 1000mg a dose not to exceed 4000mg in a 24 hour periods is the standard… well, was, its been a while since I was a pharmacy tech.