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.
A headache every morning sounds like a different medical problem that may have a more permanent solution. You may want to consult a medical professional about that. When you do, you may as well ask about the risk to your liver.
The problem with acetaminophen is that it’s perfectly safe and kind of a wonder drug, right up until your liver is overwhelmed and the stuff suddenly turns into a strong liver poison. I’m no doctor so I can’t tell you if your medicine and coffee go by the same chemical pathways or if it poses a risk to overwhelming the specific cells that deal with the painkillers, though. I don’t think coffee and Ritalin need to be broken down by the liver, but I’m no doctor.
However, every package of acetaminophen I’ve seen states that you should not use it for longer than a few weeks at a time without consulting a doctor. That’s regardless of any other medicine you may be using, or sticking to the maximum dosage. It can be totally safe to use, but a medical profesional needs to make a judgement call on that. They may, for instance, want to do bloodwork to check that your liver isn’t damaged in any way before they clear you.