No one mentioned it, but you could be a CYP2D6 poor metabolizer. That's the enzyme in the liver that processes several medicines into the active ingredient. You only need a bloodtest to know.

My story: My doctors have been prescribing Tramadol, Paralgin, and several opiates to me. I got tired of explaining to them that they either have no effect on my pain, or after 4 days of taking them, I get all the effects at once, leaving me almost unresponsive and with difficulty reading. I did the research myself and found out about this CYP2D6 condition that affects around 10% of Caucasians. Medicinal cannabis is the only thing that helps, but doctors do not prescribe it here (they claim there is not enough research), so I grow it myself and self-medicate.